But it's happened at the highest levels of golf. In fact, in 2013 it happened on the PGA Tour and the Web.com tour on back-to-back days!
On Sept. 14, 2013, Justin Rose's practice swing divot struck his golf ball during the BMW Championship:
And on Sept. 15, 2013, during the Web.com Tour's Nationwide Children's Hospital Championship, Hudson Swafford did the same thing - hit his golf ball with a practice swing divot:
Dumbasses! (C'mon, you know you wanted to say it, because now you don't feel so bad about the dumb things you've done on the course.)
What's the penalty? One stroke (Rule 18-2). And you have to put the ball back where it was to start with.
I love the expressions and the body language after it happened (Swafford's caddie doesn't even want to look at him):
You know what they're thinking: I can't believe I just f'ing did that. We can't either, fellas, we can't either.