I'll never understand why anyone who expends the effort to suck a penis to orgasm doesn't swallow the semen. The whole point of fellatio is to get the person to ejaculate and to consume the semen, come on people, the person is literally giving you a part of themselves and you reject it???
The best is sucking a guy while he's getting fucked and have him nutt in your mouth knowing the guy fucking him will feel his taint start to pulsate. Usually the guy fucking him will cum too Imagine what it's like for the guy fucking him to feel him cum too !
I fantasise about a cock pulsing in my mouth and the guy's cum pelting my tonsils. Sometimes it can be cool just to watch and behold the spectacle of cum spurting from the cock you've been sucking. Either way you would feel the glow of knowing that you've connected with his sexual animal, that his orgasm would not have happened were it not for your empathy and inherent knowledge of how to pleasure another male.