|Cooper on a poster for "The Hangover"
The 38-year-old actor will miss the special bond he formed with his co-stars Ed Helms and Zach Galifianakis on the set of the comedy franchise because most of his close friends live in Switzerland and he rarely gets to see them.
Asked whether his real-life friendship circle was anything like the movie trilogy's 'Wolf Pack', Bradley said: "I don't have an entourage of friends who follow me everywhere and with whom I can go crazy. But I've got childhood friends who are still around.
"Some of my best pals live in Neuchâtel in Switzerland. I went there when I was a teenager one summer when I didn't speak French at all, and learnt the language there. They were part of the rowing team I used to train with. I'm still close with my Swiss host family too."
The actor is amazed the films have struck a chord with so many people and thinks most men can identify with their dysfunctional friendships and crazy moments.
Bradley added in an interview with Swiss newspaper Le Matin: "The chemistry between the three of us is the main reason for it, I think. It's kind of every man's fantasy to have amazing friends with whom you can live it up at the age of 20, and still do the same when you're pushing 40.
"I think a lot of people see a bit of themselves in Phil, Stu and Alan."