I feel that you are drawing a false assumption based on a specific subculture or set of subcultures. You're going to need to specify the specific subculture in which you think this is a thing if you want an answer about that specific subculture's body language.

Every culture (and often subculture) has their own body language meanings. "Up" does NOT mean acknowledgment and "down" does NOT mean respect. Why do YOU think they mean that?