I have proof.

Case 1:
I wake up and look at my alarm clock. It reads 8:56.
The first word out of my mouth is “Dammit!” Why? Because I was stupid enough to forget to set my alarm for 5:45am so I could be at cross country practice at 6:30, and now had 30 minutes to get up, get dressed, eat breakfast, and get my butt over to the college so I wouldn’t be late for my class at 9:30. In this case, I used profanity to express my complete stupidity in the situation.

Case 2:
I’m driving home from class in the slow lane, going 70mph. A car comes up behind me clearly doing at least 85mph. They pull around me, let me know I’m #1 and shout some expletives. 10 minutes later, I drive by them again, going a safe 67mph while passing them on the side of the road, talking to the cop who pulled them over. I’m sure they had been saying more expletives when they saw the lovely red and blue lights in their mirrors.
In this case, the idiots clearly lacked the intelligence to know they are idiots, thus were reduced to using crude and primitive language.

Case 3:
“Dude, that f***in’ professor gave us a sh**load of homework. F*** that man. That b**** has a stick up her a**. I ain’t taking this sh**.
“
Do I really need to explain this one? Clearly they lack any kind of intelligent vocabulary, thus must stick to using simple 4-5 letter words to try and express themselves.

So don’t be stupid. Don’t cuss. Go to class so you can have some kind of intelligent vocabulary so society isn’t reduced to crude, rude, unintelligent slobs spouting 4-letter words because they have nothing else in their heads.