When breaking in to your school during the holidays, in order to steal, deface the headmasters office and generally add some excitement to another muggy summers day in a quiet market town - remember to cover your tracks.
Whatever you do, do not bury your swag of multi-coloured marker pens in the school ground under some leaves. Not underground - under a few fucking leaves.
I would also advise that you don't write your name all over the boxes in multi coloured felt-tip, in order to test them out.
When the stash was found, and the police were called, it was lucky they had Sherlock fucking Holmes on their team. It didn't take him long to figure out the culprit, and I was consigned to three days suspension, which let me catch up on some serious Let's Go Maths!.

Also: if given marker pens on which to sign one another's promotional t-shirts in a friendly display of camaradarie at a charity fun run, do not use them to deface the premises in full veiw of the teachers organising the event. Or else you will face three days repainting the local art gallery, courtesy of the ironic punishment division.

Still, our publicity whore of a headteacher had a pull strings to keep our school and her ugly mug OUT of the local papers after that stunt, so it was worth it. Plus all we did was write "BUM" lots of times with the dulex emulsion and then go over it with a thin coat, so you could still read the words if you stood at a certain angle.