Its like little convulsions interally at the base of the penis, while the head throbs with sensation. In reality i dont think there is all that much difference between male and female orgams.
Clit = Penis, Vagina = internal muscles
Guys can also create extended orgasms that last for more than 2-3 second. I can get it up to like 30 seconds in the right conditions and if I keep on the excersizes!