This article is from the Status Quo FAQ, by Mike Dimmick firstname.lastname@example.org with numerous contributions by others.
Rick was asked this question by someone on the mailing list:
it means 'Stocking Tops,' apparently. The song itself is
actually about a prostitute, as confirmed by Francis at
Reading in December 1997 (and possibly on other occasions when
I wasn't there)!. The full lyrics were included on the inner
bag of the original 'Blue For You' album, but are not included
on the later re-releases.