Horror comedies haven’t had a very good run lately, with the sloppy, sophomoric “Scary Movie” franchise leading a pack of also-rans that’s included disappointing entries like “Eight-Legged Freaks.” But “Slither” shows that the genre, though in apparent danger of extinction, can still be resuscitated. This is a great, goofy B movie, a clever homage to the flicks that filled double bills in the 1950s, combining low-brow slapstick and gory scares in equal measure. Art it’s not; but it certainly is fun.

The script by Troma veteran James Gunn, set in an unidentified yokel locale famous for its deer hunting, is put in motion when rich, bald Grant Grant (Michael Rooker, scowlingly right-on), put off once more in bed by his beautiful young trophy wife Starla (perky Elizabeth Banks), wanders off to the local watering hole and karaoke bar (a charming touch), where he runs into a slutty housewife named Brenda (Brenda James), with whom he goes off into the woods. There they encounter a blobby creature that’s just hatched from a fallen meteorite, which punctures poor Grant and starts his ghastly transformation into an alien paterfamilias with a hunkering for meat who, with the unwilling participation of poor Brenda, sires a whole slew of giant slugs that attack a nearby farm (and eventually the whole town), slinking down the throats of horrified victims and turning them into hungry zombies, psychically connected with the increasingly blobbified Grant–who by this time has become a tentacled glop of goo reminiscent of Jabba the Hutt.

Deployed against this growing menace is an array of local yahoos, including stalwart, drily humorous sheriff Bill Pardy (Nathan Fillion, managing the same air of cocky amiability he did in “Serenity”), who’s always had a crush on Starla, fat-headed mayor Jack MacReady (hilariously bilious Gregg Henry), a brace of bumbling deputies and a posse of redneck gun-toters, to which are quickly added not only Starla but Kylie Strutemyer (winsome Tania Saulnier), the sole survivor from the family in that nearby ranch house. (It’s Kylie who’s the object of the inevitable attack by slugs in the shower, and who goes through the obligatory scene–here funny as well as harrowing–in which a woman is trapped in a car overrun by slugs and attacked by her zombie kin.)

One could make a small catalogue of influences at work here, from “I Married a Monster from Outer Space” to “Squirm” and just about everything in between. What saves “Slither” from joining the debris of horror spoofs that have gone down swinging is the balance it draws between cheapjack gore effects (splattering green acid, exploding heads, a body being literally slit in two) and rambunctious slapstick (with Henry standing out). One might be inclined to call it a delicate balance, except that Gunn and his cast can’t really be accused of delicacy in any respect. Neither, though, do they go so far in the other direction that the movie slides into pointless chaos. No matter how comically gruesome or nastily funny it gets, one senses a strong hand at the rudder. It’s a juggling act that Gunn and his cast pull off with real affection and aplomb, with Rooker especially impressive for the mixture of menace and sympathy he brings to his part, even when encased in heavy makeup. The physical side of the movie, meanwhile, possesses a perfectly apt grunginess; the tacky surface provided by designer Andrew Neskoromny and cameraman Gregory Middleton fits the material just right, and Tyler Bates’s music does its job by mimicking the overblown scores of creature features from the fifties.

If drive-in theatres were still around, this would be the perfect movie to show at them. Luckily, it also works on an indoor screen. “Slither” is a hoot that will endear itself especially to those old enough to remember those halcyon old days of American International double features, side-window speakers and hot dogs you had to walk through the night air to buy. Now if you could only still get a whole carload of viewers in for a buck….