I've had probably two dozen requests or more over the years, so this is something I've had to come up with a policy for, and this is it:
1) Don't sell your performance for profit. A school fundraiser-type talent show or something, I consider that charity; that's fine.
2) You can shorten the script as much as you need to. I would just ask that you not add significant amounts of your own material, because people then get confused as to who wrote what; I understand if you have to come up with a line or two in order to bridge a large gap caused by having to leave something out. You can change or leave out curse words, but please do not get creative with your alterations. If it says "Oh, shit!" and you want to say "Oh, crap!" instead, I understand that. Please do not, as one group wanted, substitute "Oh, poopy!"
3) You have to credit me. Please, you have to. I need this to be in print ("Written by Cleolinda Jones," "from the parody by Cleolinda Jones," "adapted from the parody by Cleolinda Jones," etc.) if there is a sign, marquee or program, and if not, I need it to be verbally acknowledged in some way. If it's a video, it ABSOLUTELY HAS TO be in the video in some way, like on a title card or in the credits, and not just linked in the YouTube description or something, because the video could be reposted without your knowledge. In fact, this has happened before.
Here's why I'm so uptight about this: I gave a group permission to perform and record "Phantom of the Opera in Fifteen Minutes." They did not clearly, explicitly credit me in the video or on the YouTube page (the YT page may not have even been theirs; someone might have taken their video and uploaded it, which is why the credit needs to be in the video). What happened then was, a girl claimed she had written the material for the video. She then "sold" "her" "script" to her younger cousin (for something like $12.47, if memory serves), who then wrote her own, very close version of it and posted it on fanfiction.net. When confronted by readers of mine who discovered this and reported her for plagiarism, the younger cousin was very angry and defensive, because in her mind, she "owned the rights" to the POTO/15M material. Because she had "bought" it... from someone who didn't actually own it or write it. If my name had been in that video, it would have been a lot harder for the girl to pull that shit. The way the whole thing went down, even considering that the cousin had been deceived, was extremely frustrating and insulting ("I've never run into anyone I had to ask to take something down who then turned around like, NUH-UH, IT'S MINE! I DO WHAT I WANT! I ALSO DEMAND AN APOLOGY!" Yes, this was the "you accusatory squirrel-like person" incident), as far as I'm concerned. I really do not want to go through that again.
So #3 is, basically, "Do whatever you have to do to make sure that people understand who wrote this material and it doesn't escape into the wild where people have no idea where it came from."
Any additional questions?