The stale, weird or other similarly mediocre candy or sweet food eaten because the "good" candy is gone and the person eating it is too high to drive to the store. Desperation Candy can include but is not limited to any holiday candy older than six months, anything with dried fruit (Raisinettes) or coconut in it, ethnic candy made from unconventional ingredients, candy found between sofa cushions, and so on.
"Hey, munchie time. Where's the Reese's PB cups?"
"Gone. All we have left is desperation candy; you want peeps from last Easter or some broken fortune cookies?"