The Wolfpack is back, and this time it's Stu (Ed Helms) getting married -- to the precious Lauren (played by Jamie Chung). Stu, to the chagrin of Phil (Bradley Cooper), refuses to have a bachelor party, for fear of accidental drugging and other unmentionable mishaps, but the gang heads off to Thailand, where the wedding will take place, and somehow... it all happens again. This time, they lose Lauren's family's most prized descendant: her 16-year-old genius brother Teddy (played by Mason Lee).
Back to cause more trouble is the scene-stealing Ken Jeong ("I have a feeling if I hadn't gotten the part [of Teddy], maybe Ken Jeong would have gotten the part?" Mason Lee jokes.), and popular Thai actor Nirut Sirichanya plays Lauren's badass father, who is here to show America that Asian Americans aren't too fazed by missing appendages.
While Mason Lee has a supporting role -- as Teddy is missing through most of the film -- Lee gets to show up for all the fun parts: being harassed by Alan (Zach Galifianakis), getting in bar fights with monks, and of course, participating in the photo roll that reveals what actually happened last night.

Excerpts from a May 19, 2011 roundtable press interview:
How did you get involved in Hangover Part II?
Mason Lee: It was actually pretty simple, a big stroke of luck for me. I sent in my audition tape for an Unititled WB film; I didn't know what the film was. I sent in my tape early August and heard back a month later, and they wanted to fly me into LA. I did a pretty quick callback with Todd [Phillips], got some In 'n Out, and went back to New York. They told me about 2-3 weeks after that I had gotten the part, so I took a leave of absence from my school and went and started shooting. So it was a pretty simple audition process.
Which scenes were fun to shoot, and which ones were difficult to shoot?
ML: There was one part of the movie where I had to play a little bit of cello. My character is kind of a prodigy and is good at everything, and I played cello in high school and middle school, so I practiced for most of the shoot period, trying to get this piece down. So that day was fun, getting to show off my cello skills, I guess. [laughs]
The first day of shooting, we shot at the Oakland airport. That was really fun: first of all, because I got to meet all of the guys and work with them, but also, seeing Zach Galifianakis do whatever popped into his head made my job pretty easy, because I had to react honestly to whatever he was giving me. Zach was hilarious. The only difficult part was trying not to laugh.

Similar to the first Hangover -- during the credits of Hangover II, they have photos showing what actually happened last night. Did you guys improv that, or were there instructions? Like, please pretend you're doing this to the monkey.
ML: [laughs] The monkey would usually lead things. She was really good at improv. No, they would basically choose locations; there were countless great locations in Bangkok to shoot. They would just set aside some time. The cast members, Todd, Larry the DP and a couple prop master would come, under the radar, Todd and Larry would just go in with their crappy digital cameras, we'd just sort of do whatever we wanted, and they would pick and choose what shots they wanted. But in Bangkok, there's the potential for anything to happen, so we would just take what came.
Your father Ang Lee is a well-known director, but did you grow up in the industry?
ML: I wouldn't say I grew up in the industry. I think my dad's done a pretty good job of being a family man. I grew up on the East Coast, and my main exposure to the industry was during Christmas or summer vacation of public school: I would hang out on set. But other than that, I grew up with my mom and my brother, so a lot of who I am today has equally to do with how my mom raised me, how my brother raised me. I've been familiar with the industry, so it was probably less intimidating than if I was unfamiliar with it, but I wouldn't say I'm an industry kid or anything.
How did you decide you wanted be an actor?
ML: I did community theater back home. In eighth grade, I auditioned for my local high school's Shakespeare Company and really enjoyed it. I loved the community feeling and connection I had with the other kids. So, I guess freshman year, I decided I liked it, and it's not a bad way to make a living.
What was your dad's reaction when he heard you were going to be in the movie?
ML: He said "Whatever you do, don't take your clothes off." Which I tried not to do... and succeeded. [laughs]
He told me you need nerves of steel to be in this industry and that it was going to be a long shooting process, and that's basically all he said to me. He sort of let me figure it out on my own.
If you weren't acting, what would you be doing?
ML: [long pause] Probably working for Nuts 4 Nuts on Union Square. Or Jamba Juice.
Hangover Part II hits theaters May 26, 2011. For more information, go to the official Hangover II website.