I do like humourous graffiti.
Although the single funniest thing I ever saw while on an explore happened five years ago as we were making our way out of West Park Asylum and down to where we had parked our cars in a nature reserve...
As we climbed out a hole in the fence and started walking down the road a police car tore past us at speed quickly followed by a police 4x4 which slowed down to a crawl as it passed us, they obviously knew we had been in the old asylum but they drove off, but our hearts were in our mouths when we saw it turn into the nature reserve car park where we were headed.
As we got into the car park we saw the police 4x4 parked to one side, empty, and the officer standing some way away obviously looking for someone or something. Ignoring him and breathing a sigh of relief we headed back to the cars and stood around talking about the day and having some food etc. A few minutes later the officer got back in his 4x4 and drove off. A minute or so after that, we heard some commotion in the forest not far away and all watched in stunned silence as a middle-aged man came running at full speed out the forest, wearing nothing except a red lacey vest-top and matching womens underwear, dived straight into his car and sped the hell out of there...and we all literally burst into hysterical laughter at what we'd just seen!
And to think we all had photographic equipment on us but none of us got any of it on camera as it happened so quickly...