Hosted a small get together for some friends last night. Asian friends (female) start bad mouthing Asian men. How do I get over this?

Last night I invited some friends over to my place, two guys (one white, one asian), the white guy's asian girlfriend, and her friend. It was a jolly old time until the girl's started talking about Asian men, and inevitably, how small our penises are, and how 'gentle' we are in bed. Now, I understand we might have been a bit buzzed at this point, but I found it insulting to bring up such subjects while there were Asian men in the same room (in my own apt no less!). To add insult to injury, I jokingly mentioned donating sperm to make money at some point in the night, and the asian girl (with the white s.o.) said 'What women out there would want your genes?' Now I've known this girl for at least a year so I guess I could have taken it as friendly japing, but it still hurt nonetheless when seen in context of what she had said earlier.

I'm an 28 year old Asian man, I've pretty much been hearing this stuff my whole life. What I don't get it why I need to still deal with this stuff at THIS age. Why do people feel it's okay to talk like this in front of asian men? I am angry at myself for being bothered by stupid things like this, at this point in my life I should be well past all of that, but i'm not, and it still bothers me. I'd like to hear some thoughts from both males and females on this issue, and I'd like to hear some tips on how not to let these things get to me, as I'm pretty tired getting angry about these things, and I just want to enjoy life as much as I can at this point.