I'd play the gig, personally.
Making sure that we had "a last drink together to toast our farewells and no hard feelings".
I'd anticipate a decent laxative kicking in after about 40 minutes so one would need to time it so that things get interesting about third song in......
Oh, and a few minutes after sound check and before showtime with a spanner to detune the drums, alter the throw of the kick pedal, smear vaseline on the guitar strings and generally make sure that whatever they tried to play sounded awful.
So I'd deffo play the gig.
But then, I'm not one to hold a grudge, me. No sirree.