Origional Pranks

Take chili peppers, chop them up, and rub the сок on everything people touch a lot like doorknobs, remotes, phones, etc. They won't be able to tell when they touch it, but when they rub their eyes или something, well...yeah.

If they have a separate spray nozzle on their sink (the one Ты can take out and move), tie a rubber band around the handle and point it to where the person would be standing. Then when they turn the sink on, they get sprayed.

Replace the toothpaste with mouth numbing cream stuff.

That's all I can think of.

Grow up. That'll get 'em real good.

Fill her hair dryer with baby powder
Hide an alarm clock under her подушка and set it for 3:00 AM
Write her name on a pair of embarrassing-looking underwear(e.g. Maybe розовый with monkeys или something like that) and place them on a door handle.

:)