Crunchin'

When you don't hear a damn word someone was saying to you because you were eating a whole mouthful of chips or other crunchy food. Can also be used as an excuse for being zoned out when somebody is talking to you.

Mojo: "Mmmm, what I wouldn't do to yer sister..."
Lub: mmmnch crnch "Sorry what? I was crunchin'"
Mojo: "I said those chips must be good"

or

Wife: "So at work today the boss was being a real jerk and...(blah blah blah)...so what do you think of what he said to me?"
Husband: "Umm, I think that's great?"
Wife: "You didn't hear a fucking thing I said did you? what, were you crunchin'?"