If you’ve never seen it, director Danny Leiner’s Harold & Kumar Go to White Castle is exactly what it sounds like: a road trip movie about a couple of dudes (John Cho and Kal Penn) just trying to get to White Castle. Of course, it’s not that easy and shenanigans ensue.

Said shenanigans include (but are not limited to) a run-in with a ferocious cheetah, cameos by Neil Patrick Harris and Ryan Reynolds, and a bizarre rescue by a boil-faced tow truck driver named Freakshow. You can clearly see why it's become a bit of a cult hit. Not to mention, since the original film’s debut on July 30, 2004, the franchise has spawned two sequels and amassed millions of additional fans.

1. Krispy Kreme turned down a part in the movie.

Krispy Kreme could have been Harold and Kumar's ultimate fast food destination, but the famous doughnut company was wary of being associated with a movie that featured drugs.

2. The movie's producers had to make veggie burgers for Kal Penn.

Because Kal Penn is vegetarian, "The producers actually went out of their way to ... make little soy burgers that looked like White Castle burgers," Penn told Spliced Wire. "So I could just focus on the moment and not have to worry about all that. I probably ate about 30 of them."

3. Kal Penn had an allergic reaction while filming one scene.

In an interview with IGN, Penn recalled an uncomfortable scene in which ground walnuts were used to create dust coming out of a ventilator shaft. The problem? The actor is deathly allergic to nuts.

"They were so finely ground that I inhaled them," Penn said. "Now the only thing worse than eating nuts, where it gets processed, is inhaling them directly or injecting them. So why somebody decided to do that, I don't know. But I had to go outside for about two hours, I had to take a bunch of Benadryl, I was drowsy the rest of the day. And luckily I caught it [early]. Within 10 seconds of being in that room I was like 'There's something in here' and I left."

4. Christopher Meloni was always the first choice to play Freakshow.

And Meloni still has no idea why. “[The writers] said, ‘You know we thought of you from the beginning when we were writing this role for Freakshow,’" Meloni told Movie Web. "I didn’t know how to take that, I was like ‘You did, huh?’ I still don’t understand the logic, but whatever.”

5. Goldstein and Rosenberg were based on William Shakespeare characters.

According to The New York Times, Harold and Kumar’s best friends—Goldstein (played by David Krumholtz) and Rosenberg (portrayed by Eddie Kaye Thomas) were partially based on Hamlet's Rosencrantz and Guildenstern, as well as writers Jon Hurwitz and Hayden Schlossberg. ''We just knew Harold and Kumar had to have Jewish friends,'' Hurwitz said, ''to complete the multiracial circle we had in school.''

6. At first, Kal Penn didn’t like the way the film’s marketing played on race.

Ads for the film promoted the actors as “the Asian guy from American Pie” and “the Indian guy from Van Wilder.” In response to that, Penn told Spliced Wire. “At first ... I was like, Man, the movie is so not about that! Why did they have to bring it back to that? Then we realized that most people that are watching this trailer ... recognize us as the Indian guy from Van Wilder and the Asian guy from American Pie!”

“The trailer is funny because it says exactly what people are thinking," Cho added. "It also kind of dissipates—I think there is some unspoken measure of tension, like this is so unusual seeing Asian-Americans headlining a movie. So we kind of poke fun at that right off the bat.”

7. Jon Hurwitz and Hayden Schlossberg simply wanted to write a movie with characters that looked like their friends.

"The story is that the writers grew up in New Jersey, and they were really sick of seeing teen movies that were one-dimensional and that had characters which didn't look like any of their friends," Penn told Spliced Wire. "They were two white guys from Jersey, but they had a pretty diverse group of friends. So they were like, You know what? Let's write a film that's both a) smart and funny, and b) cast two guys that look like our best friends.” Added Cho: "There is a real Harold Lee."

8. Neil Patrick Harris was written into the movie before the writers got his consent.

In an interview with CinemaBlend, Neil Patrick Harris recalled the moment he heard he had a part in the film. “I got a call from a friend who was auditioning for this movie and he was so excited that we were going to be working together. And I said, ‘I have no idea what you're talking about.’ And he said, ‘Neil Patrick Harris is a character in this movie.' ... [My agents] read it, and then they called my attorney to find out what was going on, and then I winded up meeting with the [writers], kind of cautiously ... 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 ... And I agreed to do it so long as any changes they made had to go through me contractually ... And they were fine with that and they didn't make any changes.”

9. Battlesh*ts was inspired by Hurwitz’s high school football team.

Hurwitz told Aint It Cool News about the moment he first encountered the gross game. “When I was in high school I was friends with a couple of the guys on the football team. A couple of really big funny guys. I remember in gym class ... Those two guys, for some reason, always have to take a sh*t during gym class ... They started joking around about playing Battlesh*ts,” Hurwitz said. “They would joke around about it and I would always talk to them about that and started playing it up with them and saying things like, ‘You sank my Destroyer.’”

10. Jon Hurwitz’s grandparents used to send him frozen White Castle burgers.

The quest and craving for White Castle was apparently not purely made up for the film. “I lived outside of Pittsburgh for seven years," Hurtwitz said. "When I was there and my grandparents would come to visit us, they'd fly out to Pittsburgh and they would bring frozen White Castle burgers before they were in the supermarkets. They didn't have them in the supermarkets, so they would go to the White Castle, they'd buy like, 120 burgers ... frozen ... and bring them in dry ice on an airplane to Pittsburgh. So, it always kind of just had a special kind of part in my heart.”

This story has been updated for 2019.