I had a summer job working in my father's business. He had a beautiful young executive assistant, fairly new to the firm. We started dating secretly in violation of Dad's strict company policy. I was smitten.

One evening after work we started making love. I went to go down on her and she told me not to.   

“Why not?” I asked, surprised.

 "Your father fucked me twice today and I didn't get a chance to clean myself up.”

“Say WHAT?”

 “Oh,” she said. “I thought you knew. It’s a regular thing. Why do you think I got the job?”