To have sex

Let me die.

When one places an item on their doorknob to let others know that coitus is going on within.

The act of taking out someones door knob while there asleep with the lights off, so that you can then place your dick inside the hole where the doorknob once stood. Once the dick is in the hole you then proceed to knock on the door, in result some poor unsuspecting soul(probably one of your friends) comes to open the door, therefor having him grab hold of your dick, so that you can brag about it the next day.

To have a male homosexual encounter

Shagged, Nailed or had sex with someone

When you go to someone's house and rub your ass in their door knob but they turn the knob while your ass is still on the other side if the door and it got pushed into your anus