akenaton: I guess it depends on how the word is used. Some people use it
as an insult, and others don't.

But, across the pond, "jock" has a second meaning. It's used to describe an athlete, and some might find it to be insulting, others don't.

An example of how some people like it:
I had a teacher who was an athlete, and he would proudly say "I'm a jock" all the time.