Indignity: squared. Billy was still in the middle of fastidiously trying to wipe layers of mud off his body when Mattie launched her attack - and he looked up to her shout just in time to get a fresh faceful of mud. "Oh, is that how it is?" He sputtered with mock affront through the mess, his words broken by a hearty laugh.
He brushed the mud from his eyes with the back of a forearm and launched himself up off the ground towards his assailant. Still laughing, he aimed himself to scoop Mattie's legs out from under her, a gesture that wound send her toppling into her own mud puddle - though not without being sure to catch her with one arm around her back and ensure that she was lowered to the ground at a safe speed - and just the right angle. You don't take on someone with as many siblings as Billy when it comes to horseplay!