Switch-pitcher Pat Venditte faced off against switch-hitter Antoan Richardson

The crowd in Dunedin, Fla., for the  Pirates-Blue Jays on Sunday witnessed, in the ninth inning, one of the great at-bat matchups of our time: Blue Jays pitcher Pat Venditte on the mound, Pirates outfielder Antoan Richardson at the plate.
Venditte, a switch-pitcher.
Richardson, a switch-hitter. 
Venditte began the inning pitching right-handed, and then switched to left when Richardson came up to bat. So, while initially planning to bat left-handed, Richardson swapped sides of the plate, and thus batting helmets. And then Venditte began to switch hands again, and Richardson followed suit.
The two went on like this, switching sides in perpetuity. It's still going on, actually. 

Just kidding, there's a rule for this exact scenario. 
"A pitcher must indicate visually to the umpire-in-chief, the batter and any runners the hand with which he intends to pitch ... The pitcher is not permitted to pitch with the other hand until the batter is retired, the batter becomes a runner, the inning ends, the batter is substituted for by a pinch-hitter or the pitcher incurs an injury."
In other words, the batter gets the final call. As Clint Hurdle told MLB.com's Adam Berry, "It was a little bit comical. Because if anyone knows the rule, I think the pitcher does. He's the only one. It's not like you've got three or four guys working with this opportunity. It's fun to watch."
So, despite home-plate umpire Bob Davidson's encouragement to Venditte that he could switch again if he wanted, Venditte made the right call by staying left-handed for Richardson's at-bat. That at-bat ended with a hit by pitch (maybe Venditte should've switched hands), but Venditte did get an inning-ending double play by pitching right-handed to Jason Rogers.  
Watch the clip above for the entire encounter. It's just a wonder how anyone involved kept their left straight from their right through the whole thing.