"Funny signs" joke

These signs are not real, but somewhat funny nonetheless.
Sign in a non-smoking area:
"If we see you smoking we will assume you are on fire and take appropriate action."
Sign on the door of the maternity ward:
"Push Push Push."
Sign on used car lot:
"Second hand cars in first crash condition."
Sign on fence:
"Salesmen welcome. Dog food is expensive."
Sign at a hotel.
"Help! We need inn-experienced people."
Sign in a science teacher's room:
"If it moves, it's biology.
If it stinks, it's chemistry.
If it doesn't work, it's physics."
Sign in an office:
"We shoot every 3rd salesman, and the 2nd one just left."
Sign in a veterinary's waiting room:
"Be back in 5 minutes. Sit! Stay!"
Sign in beauty shop window:
"Dye now!"
Sign at a computer store:
"Out for a quick byte."
Billboard facing the road in front of a funeral home:
"Drive carefully. We'll wait."