Also means pork chops.
Chops as in musical ability is a term most often heard in drum corps and among professional musicians (ie, college-age and up who are music majors). Among this crowd, it is unusual for a drummer to be reffered to as having chops, because of the negative conotation of the word - most musicians who play multiple percussion instruments prefer to be called percussionists, as a drummer is thought of as a drum set player who can't read music. But anyways...
It's used as such: (spoken by a drum corps musician who has been in a particular corps for at least a year) "I've already got my chops, it's the new guys who need to worry about whether or not they'll make the corps this year."

Chops (?), n. pl. [See Chop a jaw.]

1.

The jaws; also, the fleshy parts about the mouth.

2.

The sides or capes at the mouth of a river, channel, harbor, or bay; as, the chops of the English Channel.

 

© Webster 1913.