IDST
A Midlands thing I think. Stands for "If Destroyed Still True". When you carve "Dan is gay" into his desk and follow it with this acronym, even if Dan spends 10 minutes scratching it out it is STILL TRUE.
You can also inscribe INDST so even if it is NOT destroyed it is STILL TRUE.
A second IDST can also protect the first IDST, in case someone destroys the IDST first, rendering the actual message destroyable. But that could result in an endless chain of IDSTs, which would be lunacy.
written by Gi*ger S*aps, approved by Log

Girls at my school turned this into a fucking science, with stuff like IDEMT (if destroyed even more true), IDEMTTEB and IDSTFEAE - it got to the point where they'd get so caught up in drafting the consequences of the graffiti's destruction that they'd leave out the message altogether.
written by da* upr*gh*, approved by Phil

We had 'IDBT', or 'if destroyed becomes true'. This causes a dilemma: Destroy it and it's true, or don't destroy it and everyone can see 'Danny is gay' scrawled on a desk.
written by an*nymo*s u*er, approved by Phil