Bradley Cooper sad as 'The Hangover' series comes to an end

The 38-year-old is upset about wrapping up the series and termed his time of working on the movie as bittersweet, reported Contactmusic.

"It's a little sad. It's bittersweet," Cooper said.

When asked about the lesson he'll be taking with him, he said, "Gratitude."

In the third film, Wolfpack gang-comprised of Cooper, Zach Galifianakis, Justin Bartha and Ed Helms will head back to Vegas to settle the final debt and decide to put their wild days behind them once and for all.

Galifianakis, who plays clueless Alan Garner in the films, said he would miss behind the scenes banter with his co-stars and their constant teasing.

"Without sounding too corny, there's a lot of laughing going on set. There's a lot of camaraderie. There's a lot of making fun of each other. I will miss that. I won't miss getting made fun of. But I love making fun of the other guys," Galifianakis said.

"Things that make me laugh are few and far between. I'm a little bit too jaded. It's easy for me not to laugh sometimes," he added.