Vaseline

A market researcher called at a house and his knock was answered by a young woman with three small children running around her. He asked her if she minded replying to his questions and she agreed. He asked her if she knew his company, Cheeseborough Ponds.
When she said no, he mentioned that among their many products was Vaseline and she certainly knew of that product.
When asked if she used it, the answer was "Yes."
Asked how she used it, she said, "To assist sexual intercourse." The interviewer was amazed. He said, "I always ask that question because everyone uses our product and they always say they use it for the child's bicycle chain, or the gate hinge; but I know that most use it for sexual intercourse. Since you've been so frank, could you tell me exactly how you use it?"
"Yes, we put it on the doorknob to keep the kids out."