Make a little ghost out of toilet paper and put it on the bathroom counter to spook your roommates.
Go to the campus starbucks and get a vanilla bean frap with raspberry syrup on top so it looks like blood and give it to your class friend (you know the one). A terrifyingly sweet treat!
Buy a Ouji board and play with your friends! While you are playing, push the thing around to spell out “B-O-O-B-S”. This is obviously hilarious and also your friends will be like woah, this ghost must really like boobs. Haha.
Go to a corn maze. While leaving said corn maze, chloroform your friend and then put them in your trunk. Then, in the middle of the night, bring them to that secluded tunnel underneath the train station and just as they are about to wake up, pour fake blood all over their body. Now, hide! Once they wake up, run down the stairs and act really relieved to see them. Tell them you have been looking for them for hours and thank god they are okay! Never tell them it was a prank. Let them live the rest of their life in confusion and fear.
Carve some creepy lil pumpkins! :o