Can a man drink his own semen?

Yes. In fact when girls perform oral sex (blow job) most of the time the guy cums into the girls mouth and she swallows it. There is no chance of pregnancy. It's only 15 calories and actually contains a lot of vitamins.

Sorry but the amount of nutrition in semen is very low considering it's only a teaspoon we are taking about. And the majority of women don't let him ejaculate in the mouth and swallow. In movies yes but in real life no. You can let him do that and swallow but remember that you can get STI's that way and even in your throat.