It doesn't happen as often than it possibly should with several thousand people attending golf tournaments every week - but when a stray golf ball strikes a spectator it's never good.
For the most part, the spectator ends up ok - they need a minute to recover, and they usually get a signed glove out of it.
There hasn't been a striking as spectator as when Phil Mickelson hit a volunteer at the Memorial on Thursday. The ball smashed off the spectators head and careered all the way across the fairway into the rough on the other side.
Only Phil Mickelson would then go to the person he hit and say
If you're head was a touch softer, I'd be in the fairway.
Only golf fans would laugh at a joke about someone who'd been hit in the head from a hard ball travelling at a high speed. Oh Phil.