Triffle

A man called his mother in Florida. He said to his mother, "How are you doing ?" She said, "not to good. I've been very weak."
The son then asked, "Why are you so weak ?"
She said, "Because I havn't eaten in 38 days."
The son then asked, "How come you havn't eaten in 38 days."
She said, "Because i didn't want my mouth to be filled with food when you called."