Comic releif good ideas?

last year i dressed in pj's to go to school and the year before i did a sponsored silence. does anyone have any good and different ideas to do in school for comic releif, (it has to be something that's allowed in school and nothing like waxing or shaving please). we were talkkin about everytime someone says an animal we have to make the noice e.g "COW" would be "MOO" is that stupid any more ideas?x