This ad is from the episode Pokémon Park / WWER.
Summary of SkitA TV show to end all TV shows, "The Thingy", starring Will Smith, Angelina Jolie, Alec Baldwin, Will Smith again, Leonardo DiCaprio, Shia LaBeouf, and Jessica Simpson.
Announcer: This fall, the creators of LOST, Flashforward, and something else that came and went bring you the TV show to end all TV shows. Get ready for The Thingy, starring Will Smith....
Will Smith: This is no ordinary Thingy!
Announcer: Angelina Jolie...
Angelina Jolie: Who would do such a Thingy?
Announcer: Alec Baldwin...
Alec Baldwin: I have some thingy to tell you.
Announcer: And Will Smith.
Will Smith: Hang on, wasn't I just down there?
Announcer: Leonardo DiCaprio thinks he knows.
Leonardo DiCaprio: It's some sort of thingy.
Announcer: Shia LaBeouf thinks he knows.
Shia LaBeouf: Dude, This Thingy is totally like a, a Thingy.
Announcer: And Jessica Simpson doesn't know what to think.
Jessica Simpson: Y'all ever eat a book?
Announcer: You'll never believe what the thingy is.
Will Smith: Can I guess?
Anouncer: You're not allowed to.
Will Smith: I'm not allowed to guess?
Anouncer: All I can say is....
The Other Cast: Yes?
Anouncer: Nope, I can't even say it.
The Other Cast: Oh, man.
Anouncer: But you do not want to miss The Thingy.
Shia LaBeouf: When is it on?
Anouncer: On a night so mysterious, it'll- your. Hang on a second. Actually, I can't remember. Uh, let me check my notes. Let's see... who have we got here? Will Smith, Angelina Jolie, blah, blah, blah, wow should be miss ok aaa, hmm, hmm, hmm. The Thingy! Coming soon-ish or some-Thingy. Duh, I don't think it's written yet, to be honest. (THE THINGY IS A CAKE!!!)