During the 1960s a striking man with snazzy outfits a permanent grin on his face (hence the name of this episode, big duh) is said to have visited a number of humans and according to a couple of accounts these visits are far from over. So who is this being and what does he want? A harmless man who likes to smile? And alien? A sex offender? Did Chris use our time machine and decide to go back and freak these people out?