From all indications, San Francisco Giants outfielder Mike Yastrzemski wasn't stealing signs against the St. Louis Cardinals. But he certainly wanted them to think he was.
In the bottom of the second inning with two outs, Yastrzemski hit a double. He danced around on second base and must've been yelling something or other, because he very quickly annoyed Cardinals pitcher Johan Oviedo — who clearly believed the Giants outfielder was trying to relay information to the next batter (Wilmer Flores).
The 23-year-old Oviedo stepped off the mound, pulled out a laminated card from his back pocket to presumably change up his signals, and then definitely yelled "shut the f—k up!