"I am four or five in"

Question

There is a scene in the movie Drinking Buddies where Gene and Luke are talking in a bar.

Gene: I've been ten minutes out since I got here. I had one of these, and then I said, "I'm gonna have one of those," and then here I am.

Luke: Yeah, it's hard once it starts going in.

Gene: I don't know what I am. Four or five in?

Luke: You're five in?

Gene: I might've.

Luke: Oh.

Gene: But I had a turkey burger earlier, so...

Luke: You're really keeping it together.

Gene: Yeah, I'm a quiet drunk.

What does it mean to say someone is four in? That person has drunk four beers? So if I have had three cups of coffee, can I say I am three in.?

Answer 1

You are correct

A person can be [some number] in (to a session of drinking).

You could say it about coffee (or any beverage) if the person drinks a lot of whatever it is or is planning to drink a lot of it.

Alcohol and coffee are the primary two uses of this phrase. If it's used with another drink, it's generally intended as a joking reference to the normal alcohol/coffee use.