Vandalism

A graffiti artist named Rigsy was serving community service and was painting over murals in a tunnel, which Fenton believed were just vandalism and that Rigsy was "trash". (TV: Flatline)

The Thirteenth Doctor wrote on the wall of a motel room with marker, to which Graham O'Brien protested, saying they would have to pay for that. The Doctor was unconcerned, later revealing the ink could simply vanish. (TV: Rosa)