I used to do the music shop shuffle myself.
Often, lots of other youths would be slapping away. This was all done on unplugged basses so it was pointless trying out one if you didn't do slap yourself simply because you couldn't hear it above the clickety click that was present all around! You couldn't beat 'em so you had to join 'em.
The truth be known, I was known more for influencing people away from the bass altogether I'm afraid.
I have one of Level 42's early albums (the second I think) on four track cassette. I think MK was a carpet fitter before that.
I loved it. L42 had just got The Chinese Way onto TOTP but I preferred the earlier material. I still do.