This technically doesn't count as I didn't get the bang at the place, but...
Out in my home town with my two closest pals a few years ago just after a gay bar opened. They were all up for going. I wasn't.
"C'mon Al, they'll know we're not gay..."
So I tagged along with them. In there, I got talking to a woman, a chubby 5 with acne at the bar. I was fucking steaming.
Next thing I knew we were making out on a sofa nearby. After a while she said, "We're not having sex. I've got a boyfriend".
Me: "OK". Carried on snogging.
A short while later she broke off and looked me in the eye. "Fuck me".
"But... but... you've got a boyfriend..."
"You're a good kisser..."
She dragged me into the Ladies. I was that slaughtered with the ale I could hardly find my belt, although at one point I managed to get her tits out.
At that moment we were disturbed by a loud banging on the door and a camp voice. "Get out of there! No shagging!"
I gave up at that point. We got dressed and staggered out.
By this time, last orders had been called. There were about ten people in there - my mates, staff, management and a few random poofs. All (including the poofs) gave us a round of applause as we emerged.
Turned out that the camp male who banged on the door was the manager, who was full of fake outrage as he yelled "Ooh! The ladies have been Christened by straights!"
The rest of the evening was relatively uneventful as my mates jumped in a taxi, leaving me alone with her.
We walked back to my place; on the way, I held her up by her armpits when she stopped for a piss in a hedge by a petrol station, then finger-banged her in my bathroom before blasting a full load of muck into her cunt.