Multipurpose Vaseline!

A man doing market research knocked on a door and was greeted by a young woman with three small children running around at her feet. 

He said, "I'm doing some research for Vaseline. Have you ever used the  product?"

She said, "Yes. My husband and I use it all the time."

"And if you don't mind me asking, what do you use it for?"

"We use it for sex," she replied.

The researcher was a little taken aback. He said, "Usually people lie to  me and say  that they use it on a child's bicycle chain or  to help with a gate hinge.
But, in fact, I know  that most people do use it for sex. I admire you for your honesty. Since  you've been frank
so far, can you tell me exactly how you use it for sex?"

The woman said, "I don't mind telling you at all. My husband and  I put it  on the door knob  and it keeps the kids out."