You can characterize “Scary Movie 2” fairly simply by noting that it begins with a big joke involving urination and ends with its twentieth or so gag about blow-jobs. It’s difficult to believe that it took the efforts of no fewer than seven writers to come up with this flat, terminally unfunny sequel to last year’s surprise summer smash. (And since the outcome of their efforts barely consumes seventy minutes of running-time, it’s clear they weren’t paid on a piecework basis.) As “In Living Color” and some of their earlier features showed, the Wayans brothers are a talented lot, but if the first “Scary Movie” was little more than a flatfooted raunch-fest punctuated by a few moments of genuine mirth, the present installment, rushed into production after the success of its predecessor, proves just as crude and even less frequently funny. It has some good moments, but they’re few and far between.

The target is different this time around. The earlier flick was a parody of teen slasher movies, a genre which traced back to “Halloween” and “Friday the 13th” but had recently been revived by the “Scream” series. As a result it had a rich, juicy target to exploit, and even though it didn’t do a particularly good job–relying on sniggering gross-out gags, smarmy sex jokes and gay-based shtick–it touched a nerve with the younger audience, who were devoted to the flicks it made fun of. This time around the coarse, smirky approach is the same, but the chosen target is the haunted-house movie. That’s a genre which has an even longer history than slasher outings, of course, going back to the silent era; and there have been some outstanding entries in it–“Psycho,” after all, was basically a haunted-house movie, as were “Poltergeist,” “The Shining” and even “Alien.” But the Wayans’ effort doesn’t mimic those pictures–it goes after 1999’s twin disasters, the remakes of “The Haunting” and “House on Haunted Hill,” both of which were so lame that they were essentially self-parodies to begin with (and were pretty much rejected by the viewing public, too). Even a good parody of something that was a bomb isn’t a very bright idea. And a bad parody of something good (remember when Leslie Nielsen starred in 1990’s “Repossessed,” a truly wretched takeoff on “The Exorcist”?) doesn’t work, either. “Scary Movie 2” gets the worst of both worlds: its a poor parody of a genre that, of late, has produced only stinkers.

If it were brightly written and engagingly performed, the picture might still have some life. As it is, though, it’s just dull, obvious and unremittingly vulgar. Bad taste can be amusing, to be sure, but it needs some verve, finesse, pacing and variety to work. Hence we just get an endless stream of gags involving sex (it’s doubtful that any script has ever boasted so many blow-job bits), joined by a remarkable array of casually dropped obscenities and countless bits involving every sort of excretion of which bodies are capable. Added to this already unsavory mix are lots of jokes involving physical disabilities, periodic homophobic touches, and a crassly misogynistic streak. And to make matters worse, the material is executed in a slow, heavy-handed fashion that accentuates its weakness instead of concealing it. The result is that even the rare sequences that might have been genuinely funny fall flat: an introductory “Exorcist” sketch has promise, for example, but it’s ruined by crossing way over the gross-out line.

There’s no sense talking much about the cast: they just mug, shout and run about in a frantic effort to liven up the proceedings–all to no avail. There are special effects (a possessed cat, a sex-starved ghost, and a perambulating skeleton), but though their chintzy realization is doubtlessly meant to be amusing, it doesn’t come off that way. There are also plenty of allusions to movies as recent as “Hannibal” and TV shows as new as “The Weakest Link,” but most of them go nowhere. The sad fact is that although “Scary Movie 2” will probably do big business, it’s really a pretty depressing affair.