I don't know enough about this aspect of US Air culture - are the callsigns always chosen by your squadron mates, or do you have any say in it at all?
It was just selected from the available choices, and one that wouldn't get squashed.
he was wrong to complain about it like that
This is true, and now any and all 'negative' callsigns will be attached to this whiner like they were etched on his skeleton. What a wimp. (substitute any other noun, but this is a family website)
are the callsigns always chosen by your squadron mates, or do you have any say in it at all?
Real callsigns are assigned by someone else. I've seen guys check into the RAG out of flight school with "Ace' or 'Mustang'. Dopes like that ended up with the least admirable callsigns which would stick unless and until they did something great or stupid to distinguish themselves.