Double circumcision
The act of attaining an erection while sitting on the toilet and then terrifyingly unwedging it out from under the toilet seat. This process typically involves skill or else we get our definition.
John: "yo I took a fat shit yesterday but can't have sex tonight cause I accidentally gave myself a 'double circumcision' "
Joe: "oh my god man why didn't you tell me"
Joe: "oh my god man why didn't you tell me"