It is done regardless of any gender or whose cum it actually is. Other people might find it gross but it is considered hot for a lot of people, especially gay men who are practically cum addicts! This is the practice where two gay men transfer the cum in their mouth to another numerous time until one of them drinks every droplet of it. Any of those would be just as equally hot but you may wonder how to make things kinkier than it already is? Cum swapping! It is the act of passing loads of cum on your mouth to your partner, basically allowing him to taste his own cum and then passing it to you again. Sometimes you want to cum on their face, or on their chest, on their crotch or on their ass. Sure, everyone has their own preference on what to do after cum, sometimes you would like your partner to swallow it. You would think after sex, people would have their energy drained but in porn-you would love to see what is thereafter sex, and one of the things being usually done is to exchange cum.
Sometimes the hotter thing in sex is not the actual moment of having an orgasm but what cums (pun intended) after it.
