Depending on the man, after he shoots his wad, there will be up to about a minute of extreme bliss known as the orgasm. This is when you STOP. His systems shut down, and actually reject stimulation. The head of the penis, being the most sensitive part, will actually make a guy quiver in pain if it is touched. We aren't like girls. We don't have multiple orgasms. Once we're done, don't try to keep going for at least 5 minutes, and you should really give it more time than that.

In response to masukomi

That is true, but I would estimate that most men find it unpleasant to be touched there after orgasm. The girl (or guy) should let that man decide when he's ready to be touched there again.