I do it every chance I get.
and, for those guys who "lose their nerve" post ejaculation... try this... when you jerk off, bring yourself right to the point of orgasm, but don't bring yourself over...
Right at this point, you will exude a small dollop of cum, but not have the full on orgasm, and remain at the height of arousal...
You will find yourself a lot more eager to lap it up...
Do this everytime you jerk off... even a couple of times, before allowing yourself to orgasm... and over a short time you will find yourself learning to really like and look forward to the flavor and oral sensation of cum.
once you have conditioned yourself to have that treat, eating your own will become easy and exciting, even after orgasm.