Adam and Eve
Adam was returning home late one night. When Eve confronted him.
"You are seeing another woman, aren't you?" she accused.
"Don't be silly," he replied. "You are the only woman on earth."
Later that night Adam woke up feeling a tickle on his chest.
"What the hell are you doing?" he asked Eve.
"What do you think?" she asked. "I am counting your ribs.