He’s not an expert, but he’s not a bigot. He knows about men and women and he knows that some people identify as neither, so he knows there are at least three genders, but there could be more than one “third” option, so he doesn’t want to cap it at three.

I don’t know if you meant you didn’t get the funny part or the meaning itself. I think it’s funny because it’s a question that trips up people regularly when British tabloids accost politicians with it. Biden didn’t really answer completely, but he cut through the bull shit pretty cleanly.