A wet bag of Cheetos found in the woods, if there was no rain recently in the area, the bag was likely pissed on by some animal, and since pee rhimes with chee, peetos is a perfect term for such a thing. The term came from the episode of That 70s Show where the gang was on the water tower spotting for Donna's engagement ring and Fez found a bag of Cheetos and handed it to Eric and found out they were wet, and Fez mentioned a bear must have pissed on it, then out came "eww Peetos!". I cant remember exactly how that part went as i only seen that episode once when it was new, but ill always remember Peetos.
Some dudes camping in the woods looking for fire wood:
Dude1:Hey man youre hungry? I found a bag of Cheetos here
Dude2:Awesome man (grabs then and shoves on in his mouth, then suddenly spits it out), yuck dude these are wet!
Dude3:They must have been pissed on by some animal
Dude1:(freaks out chucking the bag and falls over)Hey can i get a hand back up?
Dude1:Hell no, u touched peetos!
Dude3:Hah! U put a fuckin' peeto in your mouth too!
Dude2:(turns pale and spits up over some good fire wood)
Dude1:Hey, we could have used that wood!
Dude3:Lets leave that poor peeto eating bastard there to get eaten by whatever pissed on that bag
Dude1:Yeah man, wanna get crunked?
Dude3:Fuck yeah! Isnt that why we came here in the first place?
Dude1:Hopefully we wont get the munchies as badly as the peeto eater did
Dude3:Wait, how come he had the munchies that much more badly than we did already?
Dude1:Wait, wheres our stash?
Dudes1&3:Yeah hes definitley not worth helpin' out now, lets go back to town and mash in his basement, it better not be sketch
Dude2:(still lying in the dirt feelin, lookin, and smellin' like shit, and hes crying) Nature is a bitch!