Graffiti in the Airplane Cabin?
 

It's a common problem on public transit worldwide. Graffiti artists, frustrated in their efforts to daub paint and slash seats, resort to window carving with knives or blades. This is damage that's much more difficult to fix.

The other day, I saw limited carving of the window in the front row of United E+. I think it was on the 11:12 am flight from OAK to DEN.

Has anyone else spotted airplane window graffiti (or graffiti anywhere else in the airplane cabin)? Details please.