Signs and notices can simply indicate the bare facts about their purpose; or
sometimes the originator can enliven it with a bit of humour. Some examples:

Sign over a Gynaecologist’s Office: — “Dr. Jones, at your cervix.”

In a Chiropodists’ clinic — “Time wounds all heels.”

On a Septic Tank lorry: —- Yesterday’s Meals on Wheels

On a Plumber’s van: — “We repair what your husband fixed.”

On another Plumber’s van: — “Don’t sleep with a drip. Call your plumber.”

On an Electrician’s van: — “Let us remove your shorts.”

On a Maternity Room door: — “Push. Push. Push.”

At an Optometrist’s : — “If you don’t see what you’re looking for you’ve
come to the right place.”

On a Taxidermist’s window: — “We really know our stuff.”

In a Vets waiting room: — “Be back in 5 minutes. Sit! Stay!”

Radiator repair workshop: — “Best place in town to take a leak.”