i scared my friends by doing this at a slumber party.it may come in handy for you.me and 2 other friends who were sleeping over were asleep in one room,or i was trying to sleep anyway.in the next room,some of my other friends were talking about pouring toothpaste on us.i wanted to get back at them,so i snuck into the hallway.they couldn't see me because all of the lights were off and theyr flashlight was hidden between them.i noticed the closet was open,so i hid in there.2 of my friends got really scared because they thought there was an ax murderer in the closet,so they made my other friend close the closet door,which i opened a few seconds later.after that,they were all really scared,and they would've screamed,but they didnt want to wake my parents,so they told my friend to close the door again.she went over cautiously,and i couldnt help bursting out laughing,so they found me out.this is a good trick because it is scary,but it isnt mean,like pouring toothepaste on someone in their sleep!:^)