Karl invited his mother over for dinner. During the meal, his mother eyed his beautiful roommate, suspicious that there was more than just a "roommate" situation going on. Karl saw her staring at Ellen. "I know what you're thinking, mom, but Ellen and I are just friends."
A week later, Ellen said, "Karl, ever since your mother came to dinner, I can't find the silver soup ladle. Surely she wouldn't have taken it, would she?"
"I really don't think so," Karl replied. "I'll write her a letter to ask, though." He got a sheet of paper, sat down, and wrote, "Dear Mom, I'm not saying you took our silver soup ladle, and I'm not saying you didn't take it. But our soup ladle has been missing ever since you came to dinner."
A few days later, he received a reply from his mother. "Dear son, I'm not saying that you're sleeping with Ellen, and I'm not saying that you're not sleeping with Ellen. But if she were sleeping in her own bed, she would have found the soup ladle by now.