Though school isn’t quite out yet for UCLA students, Universal started the summer season early with its Monday premiere of “Neighbors” at Westwood’s New Regency theater.

Stars Seth Rogen and Zac Efron were joined by Dave Franco, Ike Barinholtz, Christopher Mintz-Plasse, Halston Sage, Jerrod Carmichael, helmer Nicholas Stoller, producers Evan Goldberg and James Weaver, Universal execs Ron Meyer, Donna Langley, Jeff Shell and Brian Roberts, and guests Joseph Gordon-Levitt and Jason Reitman.

Rogen called the shoot “controlled chaos,” but said he wasn’t surprised by how well Efron fit in with the other comedic actors.

“We knew early on he could be really funny and he actually exceeded our expectations,” Rogen said.

Despite the fact that Efron recently took home an MTV Movie Award for Best Shirtless Performance in “That Awkward Moment” and gave an abs-baring acceptance speech, Rogen said he never felt the need to slim down for the “Neighbors” shirtless scenes.

“I think I actually gained more pounds for this part,” Rogen said. “I knew the juxtaposition would be important and I think it played very well.”

At the Hammer Museum after-party, guests were able to relive their college days playing games of flip cup and beer pong while enjoying drinks out of red solo cups.

“Neighbors” opens May 9.