tagging
Much like, but not to be confused with graffiti. Tagging is signing your name or other representation of yourself on anywhere public. (walls, bus-stops, alleyways, paved streets, etc.) 

Unlike graffiti, tagging usually takes less time and skill as it is done in one color with a single can of spray paint or thick marker.
Man, there is some nice graffiti down in the alleyways on queen street west, I just wish these idiots would stop tagging over them. They gots no talent!

There's nothing I hate more than when I see some mailboxes with some messy tagging jobs on them.

Dude there's some pretty sick tags done down that street.