A travelling salesman was driving down the road, when nature called. There wasn't a gas station anywhere close, so he pulled over, went into a clump of trees and unzipped. That's how he got stung by the bee.
Back on the road, and decidedly uncomfortable, he remembered that buttermilk was a good remedy for beestings, so, when he passed a farmhouse, he stopped, knocked at the door, and asked the old lady who answered for a glass of buttermilk.
She brought him one, and waited at the door for him to drink it.
He was VERY uncomfortable, so he unzipped, and put it in the glass. Relieved at last, he appologized to the old lady for what he'd shown her.
"Never you mind," she said. "Married 40 years, and I always wondered how you men refilled them things. Now I know."