A "tell" in this case is domain-specific terminology to denote a behavior that provides information that the person may have been trying to keep secret. I belie

A "tell" in this case is domain-specific terminology to denote a behavior that provides information that the person may have been trying to keep secret. I believe the term comes from poker: https://en.wikipedia.org/wiki/Tell_(poker) https://en.wikipedia.org/wiki/Tell_(poker)