A couple of our gay friends give the "Eewwwww!" response when straight sex is mentioned. We get a little giggle out of it. Another of our gay friends told us about the time he woke up to a female friend (Who knew he was gay) giving him a BJ. The freak out he experienced and told us about didn't offend us.
To me it's the same as finding a certain type of food disgusting when certain other people like it. Raspberries for instance. How do you people eat those nasty things?