I wouldn't call them jokes, but there is an orthopaedic centre near us which is forever putting up posters that raise a smile with me. For example, they had a diagram of a skeleton headed 'PAIN!' in jagged lettering, then labels drawn to various parts of the skeleton labelled 'head', 'knee', 'arm' etc. It is encouraging that they know where the head and knee are, but there is no actual promise to be able to treat anything.

The current one is the statement 'Relieving pain improves your life', which I could hardly take much issue with.