Pulled Muscle Joke

Two old men were sat on a bench outside a nursing home having a chat. "How are
you, Richard?" asked George. "I'm not feeling too good today, I'm utterly
exhausted," replied Richard. "I've pulled a muscle, and it's killing me." "I'm
surprised that a pulled muscle makes you feel so tired," said George. Richard
yawned and said, "Well, it does if you pull it a hundred times in one night."