I'm thinking that you are not getting any responses to this question because revenge has such a bad connotation. When I think of revenge, I think of meanness and there's already too much of that.

However, if you were to prank someone - have it be funny and not mean - it might go better.

Fill a hot water bottle with blended leftovers or even pea soup. Keep the bottle hidden under your shirt near your chest and make a trip to the cafeteria. Your friends need to be in on this prank. When the cafeteria is full, make a loud noise to attract attention, bend over the table and squeeze the bottle. Your sludge should spew out all over the table like you've just thrown up.

You can do a Google search on pranks for more ideas.  Good luck.