Vaseline Corvette.

A guy driving through the countryside comes upon a weird sign advertising a red '68 Corvette that runs on Vaseline. The farmer who owns it tells him to take it for a test drive, "but don't go too far 'cause it's low on Vaseline." Off the guy goes, and it roars up to 100 mph and runs perfectly. But a short time later, it sputters and fails.

Meanwhile, at a nearby farmhouse, a family is just finishing dinner. The wife is proud of the meal she's prepared and suggests that she should not have to do the dishes. The older of two daughters says she has a date and cannot do the dishes. The younger daughter says she can't do them because she has homework. The father says he is the man of the house and should not have to do dishes. He suggests a solution. "Let's all go into the living room and sit down, and the first person who says a word has to do the dishes."

Meanwhile, the driver makes his way to the farmhouse, knocks, and gets no reply. He sees the family sitting stone-faced in the living room and knocks again. No response. So he walks in and says, "I knocked, but no one answered. What's the deal?" Not a word from the family. The man notices leftovers on the table and asks if he might eat them. Not a word, so the man eats his fill. "May I have a beer?" he asks, and again gets no response, so he helps himself to a half-dozen of them.

Maybe it's his imagination, but he notices the older daughter giving him the eye. "I'd like to make love to your daughter," he says to the farmer. Taking the lack of response as a yes, they go off together. On his return, he has a few more beers. "How about the other daughter?" he asks, and off they go. Soon he's proposing the same for the farmer's wife, and getting no response, he has his way again. It's getting dark, and the man realizes he must get going. He returns once more to the living room and asks the family if they have any Vaseline.
"All right, all right," says the farmer, "I'll do the damn dishes."