After eating something questionable, whether it is excessively spicy or expired, and expecting devastating gastrointestinal repercussions from doing so. After telling someone you are surprised you survived unscathed, soon after the food wreaks havoc on your sphincter.
John: "I had some atomic sauce monday and nothing bad has happened yet."
one hour later
John: "I retract my statement about the atomic sauce btw"
Jeff: "haha you got sphincter jinxed, I am adding that to urban dictionary"
one hour later
John: "I retract my statement about the atomic sauce btw"
Jeff: "haha you got sphincter jinxed, I am adding that to urban dictionary"
by Kissel Krooner June 19, 2013