When a guy lays his
cock and balls out on someone's face.
The balls need to be over the
victim's eyes, and the dick needs to be laying over the nose and the mouth (if you can reach that far.)
The name comes from the fact that this will look like the victim is wearing a medieval mask/helmet, like
King Arthur wore.
Oh man, when
Daylon was passed out drunk, I gave him
a King Arthur and took pictures. I left one in his pocket for him to find when he woke up.