If you think Cypress Hill's new single, ''What's Your Number?,'' sounds a lot like the Clash, you're not suffering a flashback to your pot-smoking days (don't try to deny them). The track is, in fact, based on ''The Guns of Brixton,'' from the band's classic album London Calling. Nosy buggers that we are, we asked the Hill's DJ Muggs, What's up with that, dawg? ''I've been a Clash fan for a long time, but I'd never actually sampled them because I thought it was too obvious,'' says Muggs. ''But one day I was listening to 'Guns of Brixton,' and I thought, This song is dope. It gave me the idea to do a song called 'Guns of L.A.''' Muggs brought the concept to his partner, rapper B-Real, who kept the music but came up with a new set of lyrics that focused on girls, not guns. Then, at the suggestion of a friend, the band brought in Tim Armstrong, from the Clash-influenced punk band Rancid, to play guitar on the track. Still, Muggs admits he was surprised to learn that it was Clash bassist Paul Simonon, not Joe Strummer or Mick Jones, who wrote the song. ''I saw his name on the publishing, and I was like, 'What the f -- -? Who's this guy?' I didn't know.'' Didn't know, or kinda spaced out the Clash lineup a few hundred bong hits back?