*facepalm*
For a adventure/knowledge/understanding
My old kenpo school had open sparring nights, and while we never got a "challenge" we certainly got visitors who wanted to push things. There was a reason all visitors sparred with the black belts first to vet them before allowing them near the students. I can only think of one time where a visitor pushed things past "friendly" sparring and then the situation was remedied by the guy he was sparring.