More than easy to convert this into a blonde joke.

Two friends meet on the street.
“I heard your brother died,“ one said. “What happened?“
“It was very sad,“ the other replied. “Lettuce klled him”
“How could Lettuce kill a man?“
“When he bought the lettuce, he asked the store owner how to keep it fresh. The grocer told him, ‘Put your head in a plastic bag, tie it tight and put it in the refrigerator.‘“