Idiom: To dig in
Tony: Hey guys! The pizza is ready, so dig in!
Joe: Should we wait for John?
Tony: No, he called and said he's not coming.
Bethany: I know your food hasn't come yet, but I am so hungry. Can I go ahead and start eating?
Chrissy: Yeah, don't worry about. Dig in!
Meaning: "To dig in" is a phrased that is used to tell someone to go ahead and start eating. Usually it is used in a situation where someone is politely waiting to eat. This idiom means, "You don't have to wait. Go ahead and start eating."