I didn’t get this joke from a couple of centuries ago until ….lol

“A Country Farmer going cross his Grounds in the Dusk of the Evening, spy’d a young Fellow and a Lady, very busy near a five Bar Gate, in one of his Fields, and calling to them to know what they were about,
said the young Man no Harm, Farmer, we are only going to Prop-a-Gate.”

If you too didn’t get it them read it out loud.