She sent the maid home for the weekend and didn't tell her husband.
In bed that night, the husband came out with the same old story, "Excuse me my dear, my stomach's playing up again and I must go to the loo" and off he went to the toilet.
She leapt out of bed and went along and got into the maid's bed and turned the light off.
When he came in silently he didn't waste any time with words but climbed in and had his way with her. After he had finished she said, "I bet it wasn't me you expected to find in this bed"
Spoiler:
