Scotch Tape---If the person smokes and you have access to the cigs. get ahold of one. Trim a piece of tape to the size of the filter butt. When they try to light and can't take that first drag it really messes with them.
Orajel or Anbessol clear liquid---Put some around the rim of their coffee cup or soda bottle. They won't have a clue anything has been done until their lips start to go numb. I was laughing so hard I was crying at the persons reaction to this