In terms of the medieval, humour is the one thing we DON'T get amongst the
graffiti inscriptions. There are a few inscriptions that might, in the right
circumstances, be interpreted as humour, (such as the 'The Archdeacon is an
ass' inscription from Ashwell in Hertfordshire) - but even here the
interpretation is highly suspect. We also don't get the lewd or smutty
graffiti amongst the medieval inscriptions, in stark contrast to Roman
graffiti. So medieval graffiti has no jokes and no smut... bad choice of
study area I guess...