Here's a bad old joke: What do you call a 500-pound gorilla? You call it ''sir.'' And what do you call Step by Step, the fourth album from New Kids on the Block, the only current group able to make teenage girls scream?
You call it a hit, without even stopping to ask how it sounds. So it's only for the sake of dotting every i that there's any need to praise ''Step by Step'' the title song and smash first single from the album as a wonderfully ingratiating morsel of pop. It's nourished by a chugging beat and (for dessert, so to speak) offers perky disco strings and a brief flash of silver falsetto from New Kid Jordan Knight.
Likewise, it hardly matters if I praise ''Baby, I Believe in You,'' an equally spiffy but slower and gentler pop/dance cut, or ''Let's Try It Again,'' a sweetly gushing ballad. And only a curmudgeon would bother pointing to other tunes the majority that aren't quite what they pretend to be.
''Games,'' for instance, presents itself as tough-edged rap, in which the New Kids (drawing on their Boston origins to rename themselves, rap style, the Beantown Posse) declare themselves ready and able to ''even the score'' with those who bad-mouth their music. Anyone who believes that probably also thinks that Luxembourg is armed with a nuclear deterrent.
''Happy Birthday'' is packaged as '50s doo-wop; the result is more like doo-wop and water. ''Tonight'' comes on as something close to a Paul McCartney song, which at least is a surprise; the New Kids haven't ventured into such grown-up territory before. ''Stay With Me Baby'' is make-believe reggae, or, in other words, hardly reggae at all. The real stuff would have a much grittier sound and a far more airy Jamaican lilt. Someone ought to tell the New Kids they can't adopt new musical styles quite as easily as they throw on new outfits.
But then it's not important what anyone tells them anyone, that is, except Maurice Starr, the marketing genius who invented the group and concocted every one of its synthetic songs (see related story). Two million copies of this album have been shipped, which means it can already claim multiplatinum status. Maybe soon it will be certified uranium, if the music industry cares to honor the New Kids by contriving a still more exalted mega-measure of a record's success. It makes no difference not in any way that affects record sales that most of the songs are notable mainly for their commercial sheen.