hold something in
and keep something in 1. and hold something inside ((of) one(self)); keep something inside ((of) one(self)) Fig. to keep one's emotions inside oneself. You really shouldn't hold those feelings inside of you. I have kept all this inside myself too long. You shouldn't hold in all that anger.
2. Lit. to hold in one's stomach, gut, belly, etc. Hold your belly in so you don't look like a blimp. Hold in your stomach.