Cajun term. Prank. The act of performing a bare-ass fart at or on someone's face who is either unconscious (sleeping) or not paying attention. The significance of a Shimmeashammasheaux versus a traditional bare-ass fart is that the originator unintentionally shats all over the victom's face in an explosive and most commonly diarrhetic performance. This leaves the victim with a pursuant anger, and the originator performing a prank that has "gone all wrong." Normally extraordinarily entertaining to other parties involved, and a story the victim never lives down.
My friend passed out last night and got Shimmeashammasheaux'd all over his face. It was ridiculous!