When you hear that a former child star has stolen a car during a drug binge, you usually assume that she or he is spiralling out of control, like Drew Barrymore, Corey Haim/Corey Feldman and Lindsay Lohan. But in the case of Neil Patrick Harris - who turned 43 June 14 - that story was all about him getting his career on track by playing a rowdy parody of himself in the celebrated marijuana movie Harold and Kumar Go to White Castle (2004).

Before agreeing to portray a perverted caricature of himself, Harris' career was languishing. Since hanging up his stethoscope at the series end of Doogie Howser, M.D. (1989-1993), he had starred in a number of flop features including Starship Troopers (1997) and Undercover Brother (2002). All that changed when he made the daring decision to destroy his wholesome image by signing onto the "White Castle" flick.

But his show-stealing cameo almost didn't happen because Harris was nervous about his portrayal in the film - especially since the crew hadn't informed NPH about using him in the movie before the production began casting parts. So when NPH found out he was a character in the script, he had his agents and lawyers find out what was going on, Harris told Cinema Blend in 2012.

"I winded up meeting with the guys, kind of cautiously, to see just what their plan was. Because when you're talking about an extreme version of yourself, you want to make sure you're not painted in a super shitty light. Even though it's like dark and funny and whatever, tons of drugs and strippers and lines of coke is dangerous territory potentially."

The "White Castle" crew was also nervous about the meeting because NPH was their top choice for the actor who would parody himself in the film.

"When we were writing it, we were hopeful he'd understand it wasn't a Gary Coleman part, that the joke wasn't at his expense," screenwriter John Hurwitz told The New York Times in 2006. He added that their runner-up was Ralph Macchio of Karate Kid fame.

But NPH was receptive to the idea, provided that the script didn't include too many references to Doogie Howser. He also required the crew to run all script revisions by him for approval.

"I agreed to do it so long as any changes they made had to go through me contractually," Harris told Cinema Blend. "Which I thought was very powerful and hilarious. And they were fine with that and they didn't make any changes."

And the result was a game-changer for the former child star, allowing him to become a household name as opposed to being remembered as Doogie by mainstream American audiences. As Joanna Robinson of Vanity Fair noted in 2014, "this [movie] is where Neil Patrick Harris...became a brand unto himself. It's no coincidence that Harris landed his role on How I Met Your Mother (2005-2014) immediately after this film came out. You think Doogie Howser would have landed the role of a Lothario without this performance? No way."

In case you haven't seen the movie, here's the exact scene that laid the clean-cut image of Harris to rest.

banner image: Flickr / vagueonthehow