I saw a good one at work the other week... I work at Boots and our yard is shared with Marks and Spencers, and there was a dirty M&S lorry parked up in their bay... and someone had smeared into the side of it:
I saw a lorry the other day with "British Stairways" in the BA font.. and underneath it said Domestic, Commercial and International flights.. It tickled my ribs.. :).