Ringmaster shirts are obtained through Balthazar Beauregard's Big Top Bonanza, which is a part of Distractions and Diversions. These are rewarded to players who earn more than 1,201 points in any of the circus performances. If players lose this item, they can talk to Balthazar Beauregard to obtain it. This item does not give any bonuses.
If players score more than 1,201 points, they will always get the Ringmaster hat first, followed by the Ringmaster shirt, the Ringmaster pants, the Ringmaster boots, and finally the Mega-phonus. Players will receive nothing after they have collected all 5 items, even if they score more than 1,201 points.