1. At the mall, find somebody walking by themselves (preferably not an intimidating sized person), and follow behind them relatively close for an extended amount of time. When they stop to look around, lean in close and whisper "I could have killed you", then walk away.
2. At any store or public place, make eye contact with somebody. Once you lock eyes don't take your eyes away, point at the person and yell "YOU!!!!", and then run top speed in their direction.