Reminder to all fans who are going to a Yankees game: Do not throw a ball at Brett Gardner's head.

According to Yahoo Sports, after a solo home run by Toronto Blue Jays star Jose Bautista, a 15-year-old fan caught the ball and threw it back onto the field, but he accidentally hit Gardner in the head.

It is a tradition in baseball that if the opposing team hits a home run, you are supposed to throw it back onto the field.

You can check out the video below via Twitter:

The 15-year-old fan was not ejected from the game but was issued a warning by security. After the game, Gardner was asked about being unexpectedly hit in the head, stating, "I just wore it. Didn't even turn around," he said. "It wasn't like it was coming from the second row. It was a long ways away."

He went on to joke that he has a "hard head."

Yankees manager Joe Girardi, however, was not happy with the incident. 

"Hit him right in the head, and that's kind of disappointing. I know it's kind of tradition to throw it back, but at least aim away from the players if you're going to do it, please," he said.

Girardi is not the only one to rip into a fan. Yankees first baseman Mark Teixeira blasted a fan yesterday for trying to touch him after a catch. Teixeira said, "You can insult. You can't assault. We know you are upset we lost three in a row. Keep it to insults."

He continued, "He ran into me. He really wanted that baseball. I'm all right, thank God."

You can check out the video with the fan interfering with the Yankees first baseman below:

Another note to all baseball fans: Please don't touch the players either.