It caused him to fall to the floor.
Ouch! And, guys, you know what I'm talking about.
At One Direction's concert in Glasgow, Scotland, on Tuesday night, the pop stars were chatting up the crowd when a shoe came flying onto the stage. It didn't hit anyone.
But then the other shoe dropped. Or rather, it hit Harry Styles right in the groin, causing him to collapse on stage.
With all the screaming, it's hard to tell what was being said by bandmates Louis Tomlinson, Liam Payne, Niall Horan and Zayn Malik, though they did check on their fallen pal.
Luckily, Harry was able to stand up and do a few stretches to show that he was OK.