What was your first RV noob disaster (or near disaster)?

Raised the tongue before I raised the rear stabilizers. The X-chocks let go as the tires came off the ground, and the trailer rolled backward about 10 feet, completely destroying the rear stabilizers and the tongue jack pad. In hindsight, it was probably pretty funny to see two people trying to stop 6K lbs from rolling downhill... The neighboring campers stared in disbelief and I shrunk in embarassment. Fortunately, the damage was minimal (except for my pride).