Suppose you KNEW that the pilot had a serious tree nut allergy and you had bribed a FA to let you get into the cockpit where you were going to [somehow - work out some details for this part] force the pilot to eat the single cashew while the co-pilot was [hmm, have to do something about this part of the scenario - what are the chances that both the pilot and co-pilot have serious tree nut allergies? - but oh wait, you've only got ONE cashew.....]

Yeah, that could be real dangerous to air travelers.