hey and that's a trip to HR

Just start turning it around on him and agree, "Yeah, and I'd like to do that to your mom." Say that every time. You might get him to shut up because of how annoying you're being.

Pouch him in the mouth snap his neck like a twig and then complain about the harassment

Punch him when it's over. :)

Tell him to stop cause you feel he's being disrespectful. Or make a comment about his mom instead. Or you could complain to someone.

Be a man and stand up for your woman! No one should degrade her like that

Ugh. I frequently have the same problem, I feel for you bro

duuuude not ok! I think a call to HR needs to be made!

Op you have to draw the line somewhere! if he continues he's probably going to bad mouth you infront of your girlfriend

Join in on the conversation, tell him what you do to his girlfriend as well.