How do you know when a guy is really finished?

okay, last night, my guy friend I were fooling around, I gave him a handjob.
it was the first one I've ever given.
I am so confused.
after about 10 minutes, I thought that he had started to c*m,
but when I took my hand away, he just told me to keep...

going.
he kept c*mming,
but wouldn't lose his erection.

am I missing something?
because I'm really wondering how you know when a guy is really 'finished'.

The guy is finished when he says thanx for the handjob and starts to do something else. Till he is hard that is OK to continue the handjob. Anyways, if he is not very young the sign of his cumming is the semen spurting out. But after cumming there is a period when handjob can feel better then before.

Ask him to tell you when he'd like you to stop, and don't stop till he tells you. That's it.

Most men are finished when you see them ejaculate. However, people are different. Some men like to stop as soon as they ejaculate. Others like to go a bit longer, others like to go a lot longer! So if you want to know how long your man wants you to keep going for, you'll have to talk to him about it, not us.