My BF Wants Me To Fuck His Dad

I'm a 22 F who have been dating my 23 M boyfriend for about a year now. We talked a while back about our biggest kinks and what we'd like to try with each other. I told him mine, which I consider pretty standard and a while into it, he told me he fantasizes about me being fucked by his dad. I was pretty obviously shocked and a bit disgusted when he told me this and he told me it was just a dumb joke. We left it at that for the time being and I summed it up as him kidding, but he has brought it up several times after that in pretty obvious ways. He has dirty talked about it while we have sex, we have porn in the background when we fuck sometimes and he has started putting on videos with older men and younger girls, and once he put on a video which were supposed to be a father-in-law-daughter-in-law which I turned off. He has also tried to get me to wear more revealing clothing when we're at his dads place.

I'm not interested in his dad at all, which shouldn't be needed to be said. He is a nice person, he isn't married or anything, but in his 50's, overweight, and drinks way too much and the suggestions and hints are making me really uncomfortable. Is this really a thing for you guys?