egg-beating
n.— «Players are never allowed to touch the bottom of the pool and must tread water for the duration of a game. In order to do so, they employ a water-treading technique called “egg-beating.” The players assume a sitting position in the water and rotate their legs in opposite directions. This method frees up the players” hands while keeping their position stable in the water.» —“Breathlessly, Tech polo splashes on” by Neal Turnage Roanoke Times (Virginia) Apr. 6, 2008. (source: Double-Tongued Dictionary)