No, it’s not an oversized walking creature — it’s an oozing mass of extra-terrestrial slime that looks like an angry batch of Jell-O. But this queasy-campy teenage sci-fi chiller, which gave Steve McQueen his first starring role, qualifies as an oversized-monster extravaganza, and the title says why: It’s not pretending to be anything other than a movie about … a blob. It’s elemental ’50s horror kitsch, the sort of of thing that should, by all rights, have been produced by Roger Corman, but in fact it was a drive-in special released by Paramount. The title song, with music by Burt Bacharach, goes, “It creeps and leaps and glides and slides across the floor…,” and that’s the movie’s entire plot. But if you ever catch this late at night on TV, you may find yourself hooked on the innocence of its idiocy.