(What Four?! Season 1, Episode 13, originally aired 4-26-2018) Hilarious guest Josh McClellan joins the Discovery Boys as they discover some real doozies:

1) Incredible Fossilized Footprints Suggest That Early Humans Stalked Giant Sloths; 2) Doctors Perform World's First Full Penis-and-Scrotum Transplant; 3) 'Mind-Reading' Headset Lets You Control a Computer with Your Thoughts … Sort Of; 4) A Mysterious New Form of DNA Was Just Discovered in Human Cells