Hold the phone. You do what?? That is the most horrifying thing I’ve heard all week.
Dude.
Seriously.
Blech.
Oh, yeah, the OP. Next time she had one of her little get-togethers and bought fresh pizza, when it came time for me to pay up, I’d just quietly remind her of “last time” and smile at her as I walk out.
So… you’re upset because she accepted the five dollars that you offered her in exchange for eating said pizza? I understand being grossed out at the thought of eating five-day-old pizza but, c’mon. You said it yourself that this pizza exchange is a regular occurrence. I don’t suppose she was thinking “Haha, I’ll get them to pay for old pizza! That’ll show 'em. Grr, I’m a bitch for no reason,” when she served it to you.
I do agree that it was sneaky of her to pass off the old stuff as fresh, but you ate it and offered cash for it. Gross? Yes. Inconsiderate on her part? Yes. Does it make her a bitch? Not so much.
All in all, it sucks that you ate icky pizza and it was underhanded of her. Not the worst that could happen.
This is the point where she says, “Oh, don’t worry about it - it was leftover anyway.” No, strike that - you do not serve your guests leftovers. You certainly don’t pass them off as fresh, and you damn sure don’t take money for them. What she did was one of those not done things - you didn’t know how to respond to it, because civilized people don’t do that.
Actually, I count three not done things.
Oops, my bad - yes, she did three not done things. Bad, bad hostess.
I think Stainz should 'phone this lady, loudly complaining about stomach pains.
She is actually the same ‘friend’ from this thread
DrDeth - thanks for the feedback - this is my first Pit thread (I think) … I had an amazingly long eloquent tirade all ready to go, and then I sat down at the computer, and … well, brain freeze.
I’m glad to know that with a couple of exceptions, most of my fellow Dopers agree with me that this person’s actions were* beyond* tacky!
I love pizza, but it will be a looooong time before I crave it again. Hmmmm maybe she did me a favour! 
Your first? Then, it was superb, for a 1st time rant here!