At the 26th American Cinematheque Award Gala honoring Ben Stiller** Nov. 15, Jennifer Aniston and Justin Theroux** made their second official appearance since getting engaged on Theroux's 41st birthday Aug. 10.

Aniston wore head-to-toe Valentino and flashed her $500,000 engagement ring as she posed with her betrothed on the red carpet. Before the two walked in "holding hands," according to an observer, the evening's honoree spoke to Us Weekly about the big event.

"I think it's going to be a lot of jokes, which it should be!" Stiller, 46, said. "It's going to be horrific, I'm sure!"

Stiller's wife, actress Christine Taylor, added, "I think he's the hardest working person in show business, so I am so on board! I'm so happy he gets a minute to stop and celebrate."

Inside the Beverly Hilton, Aniston was "chatting nonstop" with her BFF Laura Dern** -- and the Switch actress' presence didn't go unnoticed. "Everyone was talking about her ring," an attendee tells Us.

After Andy Dick and Jack Black honored Stiller on stage, Theroux presented a mini-movie he directed featuring "funny tributes" from his fiancee, Owen Wilson**, Tom Cruise** and Robert Downey, Jr**. "He got a ton of applause!" the attendee says. Theroux's video was followed by a more heartfelt, serious tribute from Cruise.

Other A-listers who praised Stiller included Will Ferrell** -- who joked about the Zoolander actor's penis "for a good 5-10 minutes" -- Dern and Jeffrey Katzenberg. William Shatner and President Bill Clinton also appeared in video tributes.

When Aniston finally took the stage, the actress told the crowd, "Ben makes sexy smart -- I mean smart sexy."

"His package is surprisingly large," the 43-year-old joked before presenting a video montage of her Along Came Polly costar's onscreen romances. "Very expansive, and its lasting power speaks for itself."

When Taylor gave her speech, she referenced Ferrell's multiple penis jokes -- and Theroux howled with laughter, according to the attendee. Aniston and Theroux were then ushered back to their table. "They both seemed to be enjoying the night and the company with their friends," the attendee tells Us.

Shortly after Eugene Levy presented Stiller with his award, "Jennifer and Justin, Laura, Ben and Christine and a bunch of others lingered for a bit." Before long, however, "Jen and Laura hugged goodbye" and the group went their separate ways.

"It's really nice to be honored by this and I'm really grateful," Stiller told Us. "I feel unworthy of the whole thing."

This article originally appeared on Usmagazine.com: Jennifer Aniston, Justin Theroux Honor Pal Ben Stiller at Cinematheque Awards