Open Question: Nice but funny camping pranks?

At my school we are going to the Marine Headlands and my whole class (girls) is going to be in one dorm. There is 19 of us. But also in our dorm is two counselors, there room is separate but one noise, it takes five seconds for them to come in so.... So I want to play pranks on my friends but they have to be nice and not to mean and sneaky and easy to clean up so I can get away with it and not get in trouble.

Source:
http://answers.yahoo.com/question/index?qid=20110830184342AA0RVvV

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