When you plan on saving a snack, or making it last a long time, and accidentally eat all of it in one sitting or a short period of time.
Friend 1: Bro! Bring the chicken and waffle flavored potato chips in here and let's eat some, but save the other half for later tonight.
Friend 2: Damn! I just experienced some severe premature esnackulation and ate the whole bag on the walk from the kitchen.
Friend 1: You're a raging fat ass, dude.