I want to prank a girl who I hate because she's been spreading rumours about me. I'm not really very upset about that but I still think it needs to be justified so I'm looking for some harmless and inconspicuous pranks that won't get me into trouble. My class is going on a school trip for a week and I want to take that opportunity to get back at her. We're visiting a big city and will be touring around during the day stay in hotel rooms at night. I don't want a HUGE prank because that could get everyone into trouble and ruin the trip altogether. The perfect prank would be something that isn't obvious, so it can be blamed on just dumb luck, but something humiliating or at least bothersome.