Sounds to me like an opportunity for an enterprising person to offer NCIS checks at shows for those attendees who need a stamped & dated printout to give a merchant in order to complete a purchase. Are show organizers are already providing this service?
"Sometimes I pretend to be normal, but it's boring and I go back to being me."
"You might as well be yourself, people won’t like you anyway."
"Tres verbo dictom"