We had seen this bizarre video from Friday's Twins game, of Jared Burton decking Brian Duensing just as a home run sailed over the bullpen, but hadn't realized the mystery had been solved. The short answer: relievers have way too much time on their hands.
It kind of looks like the Twins' bullpen catcher purposely overthrew Jared Burton here to give a fan a souvenir. But that throw also might have just been terrible. Whatever. If you choose to sit right next to the visitors bullpen at Fenway, you're hereby reminded to pay attention.