Kill a pig

[rebbonk]

An aged farmer and his wife were leaning against the edge of their pig-pen when the old woman wistfully recalled that the next week would mark their golden wedding anniversary.

"Let's have a party, Homer," she suggested. "Let's kill a pig."

The farmer scratched his head. "You know, Ethel," he finally answered,

Spoiler:

"I don't see why the pig should take the blame for something that happened fifty years ago."