If you're watching the Olympics and have a heart, you, like Mr. T, have probably fallen in love with curling. There are a lot of rules to figure out if you're new to the sport, but even after you've mastered the rules, the intense yelling might take you off guard.
It's part of the sport's charm. You can hear competitors talk strategy. There's a transparency you don't often find in any sport. However, hearing the teams talk doesn't necessarily clear up what's going on with when curlers are yelling like Old Man Parker at the Bumpus hounds in A Christmas Story.
The yelling or line calling is mostly done by the skip, who is the team's captain. The skip gives the sweepers directions for what they need to do to make the shot the team is after.