Lunch room thief, a way to handle it, [details]?

If you have someone at work that can’t seem to read or respect the lunch and snack of others by eating them, and the more adamant you label the items for others to please keep hands off, this person seems to think ”That really says for me to take it”, and you and others decide to teach this person a lesson. Knowing this person loves Mexican foods if a burrito was laced with Ghost Peppers that one of you came up because this person will steal it would it be unethical, brilliant, or illegal? If it won’t be a cure for lunchtime pilfering I can’t guess what will.

Some of the content might be disturbing
http://www.youtube.com/watch?v=Gdtd5OeezK8
http://www.youtube.com/watch?v=fKzIXWUnQ2k&feature=related
http://www.youtube.com/watch?v=zHi4KZjHOQY&NR=1
http://www.youtube.com/watch?v=AXuFuN5KPbw&feature=fvw
http://www.youtube.com/watch?v=JDQXwlgb6P8&feature=related