To get fucked up or have a bad experience. Derived from the movie 'Little Nicky' where Hitler had to choose a pinapple to be inserted into his rectum on a regular basis during his stay in Hell!!
Just before an inevitable bad situation is about to occur -
MITCH: 'Pass the lube - we're about to get pineappled'
When you accidentally kill yourself on Dreamland in Super Smash Bros. Melee. This is due to the fact that the bottom of the stage looks like a pineapple.