1. The state of a gay man's anus and lower digestive tract after a rough Saturday night of drinking and bottoming during sex--often accompanied by prideful complaining, awkward wobbles, and supportive friendship
2. An event or occurrence that is celebrated despite accompanied pain or discomfort
3. A person who you love although frequently pretend to hate but are, in fact, incredibly happy with
B: How was your night?
B: Bad? Or Sunday butthole?
Both: Jeah! (high five)
S: I'm ready to graduate although I will always look back on my time here as I would a Sunday butthole