From: hamptons.guestofaguest.com:
So you can put those Asprey binoculars to good use...
Appealing: if a player thinks an opponent has incurred a foul, he will raise his mallet above his head
Bump: when a player runs his steed into the flanks of his opponent's
Check and turn: slow the pony enough to turn safely
Chukker: a time period in a polo match, lasting 7.5 minutes. A bell (hooter) is rung at the end of each chukker and players switch horses.
Divot-stomping: a half-time activity in which spectators replace divots (clumps of turf) made by horses hooves