I had always wanted to try that but none of my girl friends would do that, even when I told them I want to try that.
I have a question, if the man needs to pee and is so soundly asleep, is there a risk he would pee in your mouth?
Always that risk but it depends on the guy and the circumstances. Waking up after a party of drinking and fun - yes, he will definitely need to pee.
Otherwise, I have some friends who are able to overcome that urge when they wake up to the feeling of their cock being gently sucked.
You just have to trust your friend in that what he is about to squirt into your mouth is the creamy treat and not pee. He should be able to tell you if he needs a second in the bathroom before festivities resume.