It is very hard to stop a penalty kick. There is about a 77 percent chance that when a shooter lines up for a PK, he will score. So if you save one, well, damn, you have beaten the odds.
It's totally OK to celebrate in a moment like that. Have some fun with it, and enjoy the fact that your team has slayed those pesky probabilities. By way of example, say you're the defender for Gaziantep Belediyespor, a second-league team in Turkey, and you have stopped a penalty kick. Go ahead, man, enjoy it.
But, wait, what are you doing, man? Don't do that. Don't be the guy who hugs his goalkeeper so hard that he drops the ball and it rolls back into the net for a goal. That's stupid. Look how pissed your keeper is. And how downtrodden your teammates are. I bet you feel like a dunce now. Don't celebrate. That's not a goal.
How do you say blooper in Turkish? Oh, it's still blooper.