Actor and comedian Guy Branum (guybranum.com) of No Strings Attached and Chelsea Lately joins Matt, Andy, and guest co-host Jesse Case (twitter.com/jessecase) this week as they discuss: Rural sociology! Wasting a law degree! Calling out Guns, Germs and Steel! Quinoa: Not just for Incans anymore! What makes us fat: diet or lack of exercise? Andy's swimming past! Acai, antioxidants, and free radicals! Fake Einstein quotes about bees! Anna Chlumsky! Suicide-bombing termites! Cornell's former College of Home Economics! The UK's nationalized virginity-loss system! Fooling iris-recognition scanners! Guy outs some closeted celebrities! Andy's snail mail Nigerian scam!

Pride of Chicago Robert Buscemi (robertbuscemi.blopspot.com) guests with Matt, Brooks, and Andy this week as they dig into: Recording Set List in the UK! Space has a strange smell! Why is there vodka in space? Finding Pharaohs with missing fractals! Benford's Law! Those silly Microsoft programmers and their 0xB16B00B5! Measuring a river's meander! Oxbow lakes! Billabongs! Is impersonating a beekeeper a crime? Robert's cheerleading Hippocratic oath! Creating a complete computer model of an organism! Playing God: The sincerest form of flattery! What's an aquifer? Ethanol levels in the atmosphere are rising! Michael Winslow's work as a Prius voiceover artist! Why is every La Cucaracha car horn so wrong? Matt's science museum tooth loss!

Comedian and star of The Sarah Silverman Program, Steve Agee, sits in with Brooks, Andy and Matt to talk about: Alan Jackson's Summer Country betrayal! Bedroom ceiling star stickers! Brooks is a PR shill for Starbucks! The dark side of cornstarch! Non-Newtonian bullet-proof vests! An actual Columbia physics lecturer writes in re: the Higgs boson! Hunting elephants might not be the best idea if you're the president of a conservation group! Is the CEO of godaddy.com the worst person alive? Building a jellyfish out of rat hearts! Steve's reality TV background! The first-ever Science Speed Round! Steve's failed adolescent Molotov cocktail! Brooks trying to give himself the nickname "Reptile"! Dolphins using nonlinear math to see through air bubbles! Andy doing the Alcatraz swim! The first spiral galaxy in the universe! Open call for LA-area science-types to guest on the show! Brooks losing his phone to Summer Country! Dean Cain: Not a fan of Batman!

It's Probably Country! You may have seen the very funny Nick Turner (twitter.com/itsmenickyt) on Late Night with Jimmy Fallon, and he joins the gang this week to talk about: Brooks almost stepping on a rattlesnake! What's on YOUR Instagram? Brooks's pickup lines! Bill Nye vendettas! Robots that walk like humans! Neurological wiring predicting chronic pain! What's the worst pain you've ever felt? Pictures of Mars! How much does a rover cost? Impressions of sea creatures! The real reason for the 2012 Mayan apocalypse! Flea movies! Gay snakes! A robot that can do Brooks's job! Verbot vs. Furby! Help Brooks pick a #SummerCountry ringtone! Sunburns are red due to RNA damage! Nick doesn't believe in sunscreen!

Comedian and author of the memoir Kasher in the Rye Moshe Kasher (moshekasher.com) joins Brooks and Andy to get to the bottom of: Credit inflation among comedians! Selling fake pot! The proliferation of Genghis Khan DNA! Saving baby beluga whales! The genius of John Prine! Preventing hearing loss with AMPK proteins! Growing up with two deaf parents! Working as a sign language interpreter! Drinking a bottle of vinegar to pass a drug test! Being stuck in Hawaii drinking a space diet for four months! The dude stuck in a transparent house at Burning Man! How much money would it take to make you quit comedy? Are any jobs worthwhile? The Higgs boson -- do any of us understand its significance? Killing wolves in Yellowstone!

Jordan Morris of the long-running podcast Jordan, Jesse, Go! (maximumfun.org) and Fuel TV's The Daily Habit sits in with Brooks and Andy to dig even deeper into Summer Country while discussing: Awkward moments with Yao Ming! Papercraft ProbSci hosts! Brooks's creepy mustache! The world's biggest crocodile! Detroit's future Juggalo mayor! Male contraceptives! Replacing Maury Povich with Brooks's grandpa! The return of Tony Clifton! Super-old pottery! Leap seconds! The Wood Brothers 100-Yard Dash Challenge! Rock-scissors-paper robots! Stars Wars tourist traps! The final chapter of Captain Cook's life!

TV's Bil Dwyer (twitter.com/bildwyer) of Battlebots fame, among countless other projects, joins us in welcoming Matt back to the states with a week's worth of science news!

Comedian and former molecular and marine biology major Tony Sam (tonysam.com) helps us celebrate ProbSci's silver anniversary by delving into meaty topics including: Birkenstock memories! Brooks’s Summer of Country! Stealing boomboxes from crappy comedy shows! Brooks is going to see That’s My Boy for some reason! Andy’s Pacific Northwest comedy adventures! Tony’s work as a Caribbean aquarium biologist! Giving HIV to humanized BLT mice! Hiding at work! Protecting the ocean surrounding Australia! The Parrothead epidemic! Getting asked to leave Margaritaville! Six-pack summer! Cerveza Caguama! Staying in a youth hostel at 35! Brooks is going to Europe! Speech-learning robots! Colonizing Mars! Magic kits! The first female Chinese astronaut! More borderline-racist Asian accent impressions! You have-a dis-a-respected-a my daughter-a! A secret Air Force plane has landed! Captain Cook’s awesome story! The Probably Science book club!

Talented comedian/actress/musical improv coach/science enthusiast Eliza Skinner (elizaskinner.com) sits in with Andy and Brooks to talk about: Playing a hooker on Conan! Rocket scientist family members! The Patriot missile test launches! Hands-on science museums! More Wisconsin Dells memories! Being a woman who likes Cronenberg movies! Brooks hasn’t seen Aliens! Buy a space poster, win a trip to space! Andy trying to reunite the band Wilco in the style of Parent Trap! DC Hardcore music! Eliza’s punk inclinations! Krishna-core! Favorite modes of mass transit! Brooks is heading to Europe! Hard Rock Cafe Auschwitz? Why can’t you use your phone on a plane? Andy’s love/hate relationship with sports! More moon size debates! Confusing Sams Neil, Shepard, and Elliott! Brooks loves Tennessee Williams! Kickass seagrass! The Sesame Street sassy clam! The sitcom Dinosaurs! Professor Brooks Seven Wheelan leaves his ferret at a hotel! Poorly thought-out prank phone calls! Prosthetic robot arms! Sci-fi prognostication!

Last Comic Standing finalist and Guys With Feelings host Jason Nash (guyswithfeelings.com) joins Brooks and Andy to try to figure out where Matt is, and to dig into some of life's meatiest quandaries, including: Does Andy have a weird voice? Brooks does an awful Matt impression! Jason recruits a neighborhood six-year-old to help him beat Wii games! Rob Dyrdek moves into Jason’s neighborhood! More weirdness about Andy’s roommates! Are we The Avengers of comedy and science? The science of superheroes! Bruce Jenner and The Hulk! Private spaceflight! The eclipse! Co-ed future showers in Paul Verhoeven movies! Parenting advice from Jason! Hippie houseguests! DNA tests of Bigfoot specimens! Favorite mythical creatures! The “Exotic Becomes Erotic” theory of sexual orientation! Prostate screening: Not as fun as it sounds? A Mongolian T. Rex skeleton goes up for auction! Visiting the dystopia that is LG's headquarters in Gumi, South Korea! The science behind toy envy! Tobey Maguire tries to rally the crowd at a Roger Waters concert!