“Monsters Inc.” was a huge success for Disney/Pixar, drawing in crowds of all ages who instantly fell in love with the acerbic cyclops Mike and his buddy Sully. Now, a trailer has been released for the upcoming “prequel”, which explores the early days of the monsters and how they met: in college.

Of course, “Monsters Inc.” touched upon the subject of a monster college a bit in talking about the rigorous training a young monster has to go through in order to learn how to scare properly. But “Monsters University” explores their scare learning in depth, and highlights the love/hate relationship that Mike and Sully perfected over the years.

Billy Crystal and John Goodman are both back to reprise their roles as the lovable monsters, as are Steve Buscemi and John Ratzenberger. Joining the cast this time around are Kelsey Grammer–who worked with Ratzenberger on “Cheers”–and “The Hangover”‘s Ken Jeong.

The trailer shows Sully’s prankster past as he pulls a fast one on Mike while he’s sleeping:

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And a wild dorm party:

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Mike seems to be the dorm nerd and doesn’t realize he’s the butt of the joke…

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…Until his classmates make it evident.

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Apparently Billy Crystal, well-known for his ad-libbing abilities, came up with several lines on the spot when recording Mike’s part for the trailer, and Pixar execs liked them all so well, they recorded four different versions of the trailer. You can head over to the “Monster University” Facebook page and check them out, as well as vote on your favorite.

“Monsters University” opens in June of 2013.