My Gramps was a self proclaimed “bohunk” of Bohemian ancestry. He preferred bohunk over bohemian, as (in his mind) bohemians should be smoking pot, reading poems, wearing black.
Like calling someone a pollack, I think if you are of the blood, you can get away with it a bit easier - maybe a LOT easier- than someone not.
I tend not to make pollack jokes because I’m not Polish. However, my mom is. She calls my dad a “Dumb pollack” often (he’s German. Go figure.). I just don’t feel comfortable with it.