tms - abbreviation of 'the mighty sketset'
usually a group of girls who go to parties and end up doing sexual things with random boys they do not know that they will either regret or be teased about the. however they never seem to be ashamed as they define themselves as 'mighty' and also have thier own themetune!
"oh my gosh did you hear about them girls last night?"
"yeah! they must be in sketset."
"oi, what was them girls saying?"
"ohh sketset lalalaa, it's thier themetune, thier in tms you see"