There were many minor acts of rebellion as a kid from not polishing my shoes before the meeting to underlining random sentences in the WT (without a ruler - oh horror! :) ).
However, my first public act was skipping a Sunday meeting as a 15? year old. I was with some worldly(!) friends and they were going to a motorbike scrambling event across a few miles of fields. So we all walked there and had great fun watching the dirt-tracking.
Just to rub it in, we were all standing around chatting at the end of the road when my father drove past with his jw friends. That went down well, I can tell ya LOL.