The very sight of Will Ferrell is funny.

With his frazzled hair and vacuous stare, the towering comedian always looks like he just finished speaking in tongues … and he’s about ready to tackle you.

In “Old School,” Ferrell’s dopey but funny new film, the comic streaks naked (extra naked), gets set on fire, French kisses another man, sings the Kansas song “Dust in the Wind” at a funeral and performs rhythmic gymnastics in front of a crowd. His reckless abandonment to generate a laugh at any cost is infectious.

Despite a seven-year stint on “Saturday Night Live” that resulted in dozens of hilarious characters, his movie career has proven uneven. For every good bit he’s delivered — as the accident-prone henchman Mustafa in the “Austin Powers” flicks or playing a vain Bob Woodward in “Dick” — Ferrell has suffered through some less-than-stellar gigs.

Much of this can be blamed on his former TV producer Lorne Michaels, who is notorious for forcing new cast members to sign contracts that compel them to appear in “SNL”-related properties. Thus the explanation for Ferrell’s involvement in “A Night at the Roxbury” and “Superstar.”

Luckily, the actor makes a legitimate connection with “Old School.” While he shares star billing with Luke Wilson and Vince Vaughn, the wild card Ferrell is the comedic core of the picture.

Ferrell plays Frank, a 30-ish man who is getting married, much to the chagrin of his buddy Mitch (Wilson), a real estate lawyer who recently broke up with his wanton girlfriend, and Beanie (Vaughn), a wealthy owner of an audio store chain who is a husband and father.

When Mitch moves into a house neighboring the college campus (the fictional Harrison University), Beanie schemes to use the place as a sanctuary for his domesticated pals. Soon, the location is party central, with girls, booze and live rap performances available at all hours.

Will Ferrell, center, plays an adult who attempts to relive his fraternity days in the comedy Old

Frank’s new marriage suffers as the result of a return to his hedonistic ways when he was known as “Frank the Tank.” Meanwhile, Mitch gains the nickname “The Godfather” for his apparent governing lifestyle.

Before long, the three are turning their little haven into an actual fraternity and recruiting all sorts of pledges both young and old. This doesn’t sit well with the university’s conniving Dean (Jeremy Piven), who has a past score to settle with the three men.

This escapist male fantasy benefits from better-than-average casting and some amusing moments of improv by Ferrell and Vaughn. Co-writer/director Todd Phillips shows real improvement following his lame teen comedy “Road Trip,” even though this effort is a lot like that movie as if interpreted by smarter, older characters.

The female roles (Leah Remini and Ellen Pompeo, among others) are mostly eye-candy, but the film is hardly banking on women as its target audience. However, everyone will probably enjoy the bizarre walk-ons by celebrities, some playing characters (late-night host Craig Kilborn shows up as an arrogant boyfriend) and some playing themselves (political pundit James Carville).

“Old School” noticeably lags in its third act when the fraternity is forced to compete for the right to remain a part of the school. This results in ridiculous, contrived gags (do we really need to see the “fat kid” ace the gymnastic vaulting test?) that fall flat as often as they generate a laugh.

Part of the hitch is the movie opts for a traditional good guy vs. bad guy climax. The unnamed Dean might as well be called Dean Wormer, because he and the script’s finale are straight out of “Animal House.” It’s not that ripping off that collegiate classic is unwarranted, it’s just that it seems to be the wrong ending for a comedy primarily concerned with the internal conflicts of these adult individuals.

But then there are those numerous sights of Ferrell — as when he accidentally shoots himself in the neck with an animal tranquilizer and groggily interrupts a children’s birthday party. Who needs John Belushi when you have that?