I'm going to say my half brother is not the father of his gf baby because the baby is white
He didn't see the baby yet?
I'm just kidding. Actually, I'm not very close with them because of my skin color.
You shouldn't joke like that to your brother. It's stressful to be a father and giving him the bad news of not being a father as a joke will make it worse.
I'm just joking and it's not a big deal. Everyone will laugh longer if I tell someone else. It doesn't upset anyone of mean anything,
Humor is a good trait when used correctly. Using that joke during the birth is not appropriate and could lead to family tension.