Taking the Piss*

 A man on crutches

carrying a catheter bag

full of urine

leaves St. Paul’s Hospital

wearing a tee-shirt

that says:

Dreams start here.

*According to Wikipedia “Take the piss” may refer to the expression piss-proud, which, and this is a stretch, in turn refers to the morning erections caused by a full bladder pressing upon nerves that help affect erection. This is considered a “false’ erection, and hence someone who is “piss-proud” would be taking credit where none is due, and taking the piss out of them would be an attempt to discredit them using mockery.

Another theory is that back when urine was used in the process of fixing dye to wool, urine was brought by canal to the wool mills in the North of England. Naturally transporting urine was less rewarding financially than transporting, for example, wine, so when asked what they had on board the boatmen would reply “I’m taking wine”. The inevitable reply to this would be “No, you’re taking the piss”.

This could all be true or perhaps Wikipedia is taking the piss.

https://en.wikipedia.org/wiki/Taking_the_piss