Clever Mom

A Mom visits her son for dinner who lives with a girl roommate.
During the course of the meal, his mother couldn't help but notice how pretty his roommate was. She had long been suspicious of a relationship between the two, and this had only made her more curious. Over the course of the evening, while watching the two interact, she started to wonder if there was more between him and his roommate than met the eye.
Reading his mom's thoughts, the son volunteered, "I know what you must be thinking, but I assure you, we are just roommates."
About a week later, his roommate came to him saying, "Ever since your mother came to dinner, I've been unable to find the silver plate. You don't suppose she took it, do you?"
He said ,"Well, I doubt it, but I'll email her, just to be sure."
He sat down and wrote :
Dear Mother:
I'm not saying that you 'did' take the silver plate from my house, I'm not saying that you 'did not' take the silver plate .. But the fact remains that it has been missing ever since you were here for dinner.
Love,
Your son
Several days later, he received an email from his Mother which read:
Dear Son:
I'm not saying that you DO sleep with your roommate, and I'm not saying that you DO NOT sleep with her. But the fact remains that if she was sleeping in her OWN bed, she would have found the silver plate by now, under the pillow…
Love,
Mom