A blond woman walked into a gas station and asked if they sold "710 knobs".

The mechanics all looked at each other and asked, "What is a seven-hundred-ten knob?".

She replied, "You know, the little piece in the middle of the engine, I have lost it and need a new one".

She replied that she did not know what it was, but this piece had always been there.

The mechanic gave her a piece of paper and a pen and asked her to draw what the piece looked like.
She drew a circle and in the middle of it wrote 710.

He then took her over to another car which had its hood up and asked
is there a 710 on this car?

She pointed and said, 'YES, its right there.

If you're not sure what a 710 knob is see below

710 Knob-710.jpg