I love this phrase. Sure, I know, I could find other phrases that say the same thing, but there is just nothing that says it quite as clearly. And it can be changed to Where the fuck, who the fuck, when the fuck and why the fuck.
Wickepedia says about the word fuck: "By extension it may be used to negatively characterize anything that can be dismissed, disdained, defiled, or destroyed and may also be used as an intensive." "In "what the fuck?!", it serves merely as an intensive."
Of course anyone who knows me well knows I have no reservations saying fuck. I try to hold back in the company of people I do not know well, but once in awhile I'll let it slip. I don't think I've chased anyone off yet.
I'm still sorting out exactly why there can be a negative reaction to swear words. I don't think it shows that anyone is any less intelligent or that it would make someone appear trashy. Some of the smartest or well thought of people I know use them quite frequently. And, we go back to the first paragraph. There is more than one way to get the point across, but those usually aren't as satisfying as a good old "what the fuck" accompanied by a look of total bafflement.
"That's fucking bullshit" is another good one. Short, to the point and no one misinterprets that. Of course you could say "you're lying" or "you're crazy" but it just doesn't have the same impact.
They are great for quick succinct clarification. They are great for blowing off steam. They are great for getting people out of your face.
Some people are funny about the swear words they use. My mother said she didn't like the word piss because her grandmother (on the farm) never said she was going to the bathroom, she said "I'm going to piss". My mother only said two swear words, "shit" and "damn", and she rarely used those. When those words could be heard around the house you knew someone's ass was in DEEP shit!