You probably need one of these if you don't already have one. They are about $10 at Amazon or Wally World. Of course, no matter how prepared you are, something won't quite match up. Some parks just stub unthreaded thin wall PVC out of the ground and use a slip on cap. It's always handy to have a roll of Gorilla Tape just in case.
Always remember you're unique, just like everyone else.