Legend has it Dr. Seuss wrote “Fox in Sox” on a dare to see if he could write a book using only 120 simple words. “Grind” seems to have been written on a similar dare, to see if a coherent, entertaining screenplay could be written using only the words “dude,” “man” and “bro.”

I have exaggerated the lack of depth in the screenplay for “Grind,” but not by much. It was written by Ralph Sall, who has a couple dozen “music supervisor” credits, but is taking his first stab at writing here. I don’t recall what the music in “Clockstoppers” or “Three Kings” was like, but it surely can’t have been worse than the writing in “Grind.” This is a film that believes quality humor is humor that involves Porta-Potties tipping over and hapless teens having to clean them.

Part road comedy, part skateboard movie, this is the story of three Chicago-suburb teens, fresh out of high school, who desperately want to be professional skaters. To do so, however, one must become “sponsored,” which in these guys’ case will involve catching the attention of their skateboarding idol, Jimmy Wilson (Jason London), and getting him to recommend them.

Unable to gain an audience with the Pope-like Jimmy Wilson, the threesome does what any reasonable group of lads would do: They get summer jobs and prepare for college.

No, I kid. Obviously, they obtain a van and follow Jimmy Wilson around the country on his skating tour. They figure if they can just weasel their way into one of the venues and do some skating, Jimmy Wilson will see them and make them stars, hopefully before they are chased out by security. (The boys’ plan is not fabulously well thought-out.)

Allegedly, they are fantastic skaters and deserve to be professional at it, to the extent that anyone really “deserves” to be a professional skater. (Is anyone a professional jump-roper? Hopscotcher? Just asking.) It’s hard to say for sure, though, because every time they skate, they are filmed from the waist down, or from behind, or in some other way to obscure the fact that it’s real-life pro skaters doing the tricks, not the actors, who probably don’t skate very well.

Ah, yes. The actors. The three boys fill the roles normally prescribed in the Three-Man Buddy Comedy. You have Eric (Mike Vogel), the fairly normal, slightly level-headed guy. Then you have Dustin (Adam Brody), who is uptight and nervous. Then you have Matt (Vince Vieluf), who is wild! and crazy! and so unpredictable!, filling a role that in a bygone era might have gone to John Belushi, but which now goes to the likes of Tom Green (who makes a cameo himself, by the way).

Oh, and they apparently have a fourth friend, who I guess also wants to be a professional skateboarder, only not as bad as these three, I guess, because he’s not involved in the initial planning stages. Anyway, his name is Sweet Lou (Joey Kern), and he’s a friend to all the ladies, and he has a van.

I need to talk about Matt some more, though. You may recall Vince Vieluf as the guy who wasn’t funny in “Rat Race” (well, ONE of the guys who wasn’t funny in “Rat Race”). In this movie, though, he plumbs new depths of non-humor, basing his character entirely on the twin philosophies of 1) making a lot of goofy faces and weird noises; and 2) being an oversexed horndog freak borderline sex offender. He is spectacularly unfunny, making a film that is otherwise dull, tedious and interminable into a truly grating affair.

You know who I like, though? Adam Brody, who plays the uptight friend. He delivers a few lines well enough that they seem funny, which none of his co-stars can manage. He’s good in the new Fox series “The O.C.,” too, playing a similarly flustered, slightly nerdy character. I think he has talent.

Oh, but the rest of the movie. It’s listless and quiet, like it’s not even trying most of the time, forgetting for what seems like hours at a time that movies are supposed to have stories. It culminates in an orgy of skateboarding, filmed with only a mediocre level of ambition or skill. You’d be better off watching actual skateboarding on ESPN2, not this tiresome crap.

F (1 hr., 43 min.; PG-13, some profanity, a lot of crude humor, some partial nudity.)