Although Neil Patrick Harris will always be known for his breakthrough role as Doogie Howser M.D., a lot of fans might not know that Harris has also been the voice of several characters in the animated Spider-Man world and the small-screen cartoon Justice League universe. Although Neil Patrick Harris has gone on to bigger and better heights after Doogie Howser, both on the stage and screen, he also found hilarious success in Harold & Kumar Go to White Castle back in 2004.

Flash forward four years and Harris has found a regular home on the ABC comedy How I Met Your Mother and now returns to the big screen to play himself for a second time in Harold and Kumar Escape from Guantanamo Bay with John Cho and Kal Penn. While kicking back with the press at the recent Harold & Kumar junket, Neil Patrick Harris had fun chatting about playing the legend of himself, keeping Doogie Howser at bay, the massive 65-NN size of a character's breasts, and the recent appearance of Britney Spears on How I Met Your Mother.

Neil Patrick Harris on letting himself go to the dialogue:

"Well, I don’t feel like I abandoned much of anything. I was anxious to read it to see if it would be as funny as the first, or if they would’ve truly jumped the shark and I found it hilarious. When someone writes a 'Neil Patrick Harris' character doing crazy things and it’s these guys writing it, I’m all for it. I was very excited to do it."

Harris on playing the legend of himself:

"I don’t know what to make of that. I mean, I can’t take any of that seriously at all. But it’s funny to play someone that everyone is so gaga about. It’s weird, I don’t know. I mean, there’s website about what would NPHdo.com and that’s me. I don’t know, it’s all very strange."

On whether his role in the first Harold & Kumar helped him land his role in How I Met Your Mother:

"Yeah, no question. Carter [Bays] and Craig [Thomas] even said so. I don’t think I would be playing the strong alpha-male guy if the first had not happened. And that was Jon [Hurwitz] and Hayden [Schlossberg] writing it wondering if I’d do it and me sort of climbing on to the idea of getting to play someone like that. And I think that allowed Carter and Craig, in turn, to see that I could play that kind of lead."

On the idea of writing his character as Doogie Howser:

"Yeah, but they didn’t write it like I was in a stethoscope and a lab coat, [with a] 'will work for food' sign or anything like that. They were very reverential about it. You know, that was my only concern. I didn’t want to disrespect Steven Bochco or the show because it provided me with an exorbitant amount of experience and that’s not my style. I wouldn’t want to sort of sh*t on my past to have a future, and they were cool about that. And I appreciated the joke that someone who seemed squeaky clean as young Dr. Howser was now sort of tripping on 'X' and doing lines of coke off of a chick’s ass in their film. I thought that was a funny dynamic. But I also had it put into our contracts that any rewrites that had to do with me, or any scenes regarding me, I had to have approval on before they got in the script. I didn’t want them to film scenes and then start filming other scenes where people come in and said disparaging jokes."

Neil Patrick Harris on the size of Tits Hemmingway’s breasts:

"Oh my god... Big! This woman, we just looked her up. Her name is Echo Valley, her breasts are - hold on - hey, it’s almost 4:20 look at that, she’s had eleven surgeries... [searches his cell phone] Wait, here it is, ‘Echo Valley Big Tit Pictures.' I want to get the size right. I know it’s Double-N, but let me figure out what the number is. I’m just still amazed she chooses the name Echo Valley, which is like a vaginal surgery that needs to happen. She had a small 32 AA chest. After eleven surgeries she’s now up to a monstrous 65 NN."

Harris on the back story of his character:

"I would love to know the answers to certain questions. Jon and Hayden, I think, actually have answers to those questions. Not like improvy, riffy-like - I think they actually know why he was thrown out of the car in the first movie and ended up hitchhiking on the road and how he got all of the ecstasy. I think they know what the jar of hair in his bag is for or how it came to be. I didn’t ask, but I’m interested to know myself."

Neil Patrick Harris on having Britney Spears appear on How I Met Your Mother:

"I was amazed. I was very amazed by it all. From being on set and hearing rumors that she had called and was interested in being on our show, I was amazed through her showing up, through all of the press and watching people try and sneak on the set, and through the ten million people that ended up tuning in. It was all a very interesting couple of weeks."