They can always claim it's a parody which is protected under the first amendment but lawyers from Hollywood would still be suing and the film would probably be stuck in developmental hell for all eternity.
For instance one of the biggest fads from YTMND was an obscure Nick Jr show called LazyTown. You might have heard of LazyTown due to the highly successful meme, We Are Number One which helped raise awareness for Stefan Karl's pancreatic cancer and helped cure it. However at one time LazyTown didn't embrace the meme that spawned from YTMND. YTMND had made LazyTown look like a creepy kids show due to a 14 year old girl with pink hair and 2 adult males on the show and the rest of the characters were puppets.
The other problem with a YTMND movie would be the whole plot of the movie. This would be a huge block when it comes to what the point of the movie would be. I would assume if a YTMND movie would ever be made it would be like the 1941 Olsen and Johnson movie Hellzapoppin'. I love Hellzapoppin' it's total insanity with tons of slapstick and running gags, just like YTMND fads have.
If a YTMND movie was ever to come about, getting certain actors to reprise their roles from the classic movies and TV Shows that Made YTMND what it is would be a huge problem. For instance several people that YTMND fads were based on have since passed away such as Brian Peppers, Gene Wilder have in recent years.
|South Park's Disclaimer|
Now by having a sort of disclaimer like the ones that are seen on South Park and Robot Chicken is probably the safest bet to go with if they do make a YTMND movie. The Robot Chicken disclaimer best describes YTMND in a nutshell especially the parody manner.
Although it would be cool to see a movie based on YTMND fads coming together, the chances of that happening are slim to none. If your looking for a YTMND movie you could just watch Finding Forrester which inspired YTMND from the start. Or you could just watch every movie or TV show that made YTMND what it is today.