Toggle Switch

On the top of most automatic doors in most convenient stores such as Meijer or Walmart, there is a switch on top of the door that controls the sensor. As you walk out simply reach up real quick and flip the switch, turning the sensor off...sit back and watch as customers smash into the door as they expect the automatic door to open. Barely any people know that the switch is even there. It will cause a lot of confusion and people's reactions are priceless.

The Thief

Take/steal your friends or roommates most necessary items. The little things that they take for granted are the best. Deodorant, chapstick, ID card, a belt, anything of this nature would work. If they ask you if you took it then deny deny deny...it's not lying, it's just a prank. Strategically place the item some place in due time...or never give it back just to piss them off even more.