Dean Martin once sang a song entitled, "Ain't That a Kick in the Head," which, we're guessing, had absolutely nothing to do with sports.
But after perusing the Internet, some athletes and referees might be saying the same thing, because there are a lot of instances where they get nailed in the head completely unexpectedly.
These just so happen to be the ones we liked the most.
Unfortunately for aging NBA veteran Kurt Thomas, he learned the hard way that no one should mess with "The Manimal," Kenneth Faried.
Though it wasn't done purposely, Faried's high top knocked Thomas out of the game with a mild concussion, so it wasn't something he could just rub dirt on and get back out there.
What could possibly go wrong when organizing a backyard wrestling match?
We've probably all pulled out the spare mattress, blasted some cheesy entrance music and hoped to God we didn't break anything while wrestling our buddies for fun.
But when someone gets both a knee and a foot to the face, it's not nearly as humorous as any of us may have hoped.
Though this isn't an athlete receiving the kick to the face, the fact that former Olympic taekwondo competitor Angel Matos delivered it—following the bronze-medal match no less—makes it something the ref probably wasn't expecting.
An unintentional kick might happen every once in awhile, but this is absolutely anything but.
Manchester United and Netherlands forward Robin van Persie might be a pain in the ass to try to slow down during a match, but that doesn't mean opponents need to resort to knocking him across the head in order to do it!
OK, so this kick of the ball might have just unexpectedly nailed him in the back of the noggin, but we'd like to think it was a little intentional too, seeing as these guys can place the ball almost anywhere they want to.
One probably doesn't think of cricket as much of a contact sport, but don't be fooled, there are a lot of hidden dangers.
The paddle is something to fear in itself, but when going for a ball, a player should always be conscious of where their teammates are—otherwise a face full of leg might just happen.
Who would ever think that a home plate umpire would have to worry about a cleat coming up and hitting him in the face as a potential danger?
Foul balls off the shoulder or mask?
Sure, they take them like champs.
As we saw in a game late last year, though, trying to keep their eye on the plate can cost them sometimes.
Poor little Lionel Messi.
As arguably the greatest soccer player on the planet right now, he often takes a beating by defenders trying to knock him off the ball, lessening his impact on a match.
Standing at just 5'7", Messi might not be tall, but he had enough height for this Athletic Bilbao defender to reach his face, delivering quite the blow.
Oh, Cristiano Ronaldo, you just aren't as sly as you must think you are.
You might be able to put the ball pretty much anywhere you want to, and embarrass your opponents with crazy foot skills, but you're the one who should feel ashamed.
We expect this from some goon, but not Ronaldo, one of the top players in the world!
With all the padding football players wear—including that whole helmet to protect their heads—it's pretty rare to ever see a player get stomped on.
But after former defensive tackle Albert Haynesworth took exception to something his opponent Andre Gurode did, Big Al ripped off Gurode's helmet and took his large shoe to his face.
It may not have felt too great for Gurode, but in the end, Haynesworth's five-game suspension probably hurt the Titans defender even more—at least in the wallet.
Yes, getting kicked in the head actually happens in hockey too.
Luckily, this video shows a fan using his shoe on the glass to get his frustration across to visiting player Joffrey Lupul, rather than a skate, but it's still something that the Maple Leafs winger probably didn't expect would happen at any point on the ice.
Remember, kids: When in a fight, always keep your head on a swivel and expect anything to happen.
We guess MMA fighter Mikey Saenz didn't listen to these instructions during his battle with Vaughn Goby, who knocked Mikey across the face so hard that Saenz actually spun around.
This is the type of kick that will make a guy see stars for a couple minutes.
Though the kick itself is pretty funny because it comes out of absolutely nowhere, the best part of this video is Antonio Cassano's former AC Milan teammate Zlatan Ibrahimovic walking away with a giant smile on his face after doing it.
We actually wonder: How does Cassano play it so cool, not going after Ibra?
Seems to us that Zlatan was just pissed that he wasn't getting the attention following the match.
After watching this video, we really wonder why the hell anyone would want to step into a ring with an MMA fighter?
Even after training and getting mentally and physically ready, there's no way in hell taking licks from fists and feet sounds appealing.
And when the end result could potentially be getting stood up following a wicked knockout kick to the face, it just makes it about the least appealing thing on the planet.
In a more recent example, the Spurs Tim Duncan accidentally kicked the ball into the Grizzlies Marc Gasol's face during this year's Western Conference Finals.
Being from Spain—a soccer-crazed country—you'd think that Gasol would know to take that ball off the forehead instead of the face.
But it didn't quite happen that way, leaving quite the mark, we're sure.
There are missed calls, and then there are terribly missed calls.
This one just so happens to fall under the latter category, as the referee in this World Cup qualifier really swallowed his whistle following New Zealand's Shane Smeltz taking a boot to the face, causing some serious blood to gush from his head.
The ref should honestly be given a red card for letting play go on.
There's a lot of dancing in the beginning of the video, leaving viewers with the anticipation of the kicking knockout.
When it happens though, it's crazy serious, as the kid hits the deck like a wounded duck.
Was he expecting to get kicked?
It's karate; of course he was.
But was he prepared for the way it actually happened, getting popped in the face?