the worst graffiti artist in London

There's someone who goes through Gloucester Road tube station regularly and gets their kicks from writing in blue biro on the posters in the lift. That's fairly normal, posters get defaced all the time. But the blue biro person is unusual. They specialise in stating the blindingly obvious. Blue Biro Person writes speech bubbles on the posters, saying exactly what you would expect the person in the picture to be saying.

On an ad for some Toy Story thing, BBP has added a speech bubble over Woody's head, saying "Howdy pardner! Schu gotta name?" ("Schu"??) A picture of a waiter serving a table in a Chinese restaurant now shows him saying "You like won ton?" And a cartoon of a person with sparkly white teeth, for a local dentist, is adorned with "Look, I've got a lovely smile."

I'm not sure why this bugs the hell out of me, but it does. If I ever catch BBP at it, I'll be tempted to grab them by the lapels and demand, "Why do you do this? WHY? What's the point? It's not funny. It's not clever. It's not subversive - it just agrees completely with what's happening in the poster. Even giving someone in a poster chewing-gum genitals is more subversive than that. For goodness' sake, it's not even a tag. Why?!"

Maybe BBP is making some sort of subtle point that I am too thick to get.