When your erection is only semi, it does not go all the way. This is actually more embaressing than a true boner because people think you 'cannot get it up'
HAHHAHAHA LOOK PHIL HAS A SEMI BONER OVER CHARLOTTE!
ITS PROBABLY OVER JOHNNY CAUSE ONLY HOMOS GET SEMI BONERS!
When ones penis is no longer erect, possibly either after blowing ones load, or just losing an erection. A semi-boner is often used for playfully slapping ones friends in the face while they sleep for a hilariously good time.
One of those annoying partial erections. Not quite hard enough to masturbate with, but hard enough to be seen by people if you stand up. They're also rather difficult to get rid of, because by the time you get one you want to get the rest of the erection.
Jason: brb getting milk -gets up-
Mom: You're semiboned, son. I don't need to see that.
Jason: -.-
Boys who enjoy yaoi (a genre in Japan that contains sexual and/or romantic relations between two men); literally translates to "rotten boy"; corresponding female : fujoshi