Shatan Fastarm has one arm that is noticeably bigger than the other and this is why he is on the team as a thrower.

Yes, he has heard every single joke that could be made about this.
No, he isn't going to change it because he doesn't actually have 'Strong Arm' as a skill (Yet).
No, it's not because of any nocturnal activities or lewd inclinations you might unfairly accuse him of.

It's a minor mutation he was born with and his feelings get very hurt every-time someone makes a joke about it. And when Dwarves get upset they tend to start chopping people at the knees in response.

Incidentally he is also the part time regional arm wrestling champion for 3 years running.