A young American rabbi, maybe age 30, with no real beard and not looking rabbinic at all, was having trouble with the airport security. The conversation went as follows.
Guard: What's your job?
Rabbi: I'm a congregational rabbi in the US.
Guard: Really? You don't look like one.
Rabbi: אל תסתכל בקנקן אלא במה שיש בו.
Guard: Hmm, OK, have a nice trip.