The actors rummaged through the host's things and even joked about checking out his Google history and stealing one of his Emmy awards.
And just as the stars of Dumb and Dumber To were causing a ruckus, Lauer walked into the room wearing a powder blue suit that looked identical to the one Daniels famously wore in the 1994 hit film.
"You are too much," Carrey said.
Daniels commented, "That looks custom fit, I bet you had that tailored."
After sharing a laugh, Lauer had one special request for the two stars.
"Since I went to the trouble of going all prom outfit on you, would you just give me the honor of just a small portion of 'Mockingbird' from the original movie?"
Carrey and Daniels happily obliged, fumbling on the lyrics to the song at the very end of their hilarious live rendition.
Lauer was shocked that they took him up on the offer and Daniels joked, "Yeah, I should've taken the 'no' option on that."
Last night, the two debuted the first trailer for the highly anticipated sequel during The Tonight Show Starring Jimmy Fallon.
The flick follows the two pals' search for Harry's long-lost daughter in the hopes of getting a kidney transplant.
"It's not even a movie anymore," Carrey jokingly told host Jimmy Fallon. "It's a phenomenon."
(E!, NBC and Universal Pictures are all part of the NBCUniversal family.)