Jock: a person devoted to a specific activity, jockey (definitions found weren't worded so great)
Here's what some people had to say
"Big, bulky athletes in lower classes, not really smart"
"Idiots, bulky, greasy, full of themselves"
"Strong, popular, devoted only to the sport"
"Full of themselves, popular, rude, unmotivated in academics"
"Dumb, don't do homework, party a lot, only care for sports, brag about themselves"