When you take a crap containing half feces, half gas. The solid is propelled at such a rate that the entire inside of the toilet bowl is lined in crap.

When you eat dirt for the first time and leave your family to build a shack in the woods

When it is hot outside and your balls are sweating and they stick to the side of your inner thighs, and you have to pull them off (They are sticking like wallpaper)

idiom

An act, (usually homosexual) where one party is standing, spread, facing a wall (much like when a police man performs a search). And the other member relentlessly ravages them from behind. Thus resembling two people putting up wall paper.

If a girl tells a guy a bit too late that she doesn't want to receive his special juices, he may have no choice but to ejaculate on the nearest wall. Bonus points for hanging a poster using the sticky stuff on said wall.