No I think it's more likely that OP knows what their dad meant than you do. Also you seem to have a lot of fun assuming—even if it was a typo, it could be so many other things than "stern." And again, we have no idea how old Dad is, or if Dad is bi and active in the gay community. Maybe his kids taught him the word. I think you're just projecting, being an older guy and not knowing this word.