Pig out
Definition 1 of 1
Pro Tip 1/3Informal Language
Used in casual settings among friends or at informal events, not in formal situations. 
At the barbecue, we all pigged out and had a great time.
Pro Tip 2/3Slang Origin
Comes from the idea that pigs eat greedily without manners. 
I can't believe I pigged out like that; I ate as much as a pig!
Pro Tip 3/3Negative Connotation
May imply lack of control or overindulgence in eating, often viewed negatively. 
She said she pigged out last night and felt guilty.