Unless you want to push back (clearly you don't), I wouldn't even acknowledge the topic or what about the topic makes you uncomfortable
"Hey man, this is a bar conversation. I don't feel comfortable talking about stuff like this at work."
I work in the same office as my best friend and I've told him similar - even though our politics are very closely aligned. Yes, I agree it would be funny if Trump shit his pants when he falls asleep in court. But I don't want people to hear us talking about that