A spell in which you put on a guy, and his penis gets erected, unless you are fat.
Tyrone: Yo bitch! I'm gonna knock dat tit right ndown to da core!
Yopani: Expecto Erectus!
Tyrone: Aw shit man! What da hell did you do dat? Fuckin bonars...
Yopani: You asked fo it man.
Tyrone: go down man! go down! I aint ready!