Trip orientation meeting: illegal activities

Rules of behavior. Explain that laying out rules is not a sign you don't trust them. Trust has nothing to do with it. The adults are held legally responsible for the youth. This is strictly a formality so that there are no misunderstandings or surprises:

• On some things there can be no flexibility: If you break the law (underage drinking, drugs, etc) we'll still love you and forgive you as we put you on the airplane home – at your parent's expense.
  (I had one group of boys put me to the test on this -- they bought a joke bottle of honey that looked like a bottle of bourbon.  They pretended to be sneaking it and let me catch them.  I started to make arrangements to fly them home when the revealed the "joke." We all laughed but I almost had a heart attack over it. They never tried anything unacceptable after that.)