Euphemism for sexual intercourse; specifically with a female. Alternatively, when you buy a muffin for later and is destroyed due to being left in a soft sided container.
"Dude, I heard he totally crushed her muffin last summer... that's why they don't talk anymore."
"Awww, I crushed the muffin... I really wanted that..."
Doing something exceedingly cool.
The act of being awesome.
Friend 1: Hey buddy, what are you doing tonight?
Friend 2: Crushing the muffin.
Friend 1: AAaaaaaaawwwwwwwwwwwwww yeeeeeaaaaahh!