“Fuck” gets a lot of credit for being a versatile word. You can pepper it into nearly any part of a sentence as often as you want (“Where the fuck do you fucking think you’re fucking going?”), or even use it between syllables of a word you want to emphasize (un-fucking-believable). You can tell someone to fuck themselves, or even suggest they do so after moving away from you (“go fuck yourself”) or just utter, “Fuck me.”
But “shit” is almost as useful. It certainly has quite a few variants. You got your dumb shits, dipshits, lying sacks of shit, shit bags, shit heads with shit eating grins. You can have a shitty morning, a shitty day, a shitty afternoon, or even just be feeling shitty. Psychopaths make note of everyone they hate on their “shit lists,” but if you just want to talk to someone, you shoot the shit with them. If you are really drunk, you’re shit-faced, and if you don’t care, then you don’t give a shit, or couldn’t give a shit. Then you have a whole zoo full (or shitload) of animal options.
You got horseshit and bullshit, and I never know when it is appropriate to use one over the other. It’s like the shit equivalent of “lay” and “lie” with me. Also, why bullshit and not cowshit? If someone is insane, they’re batshit crazy. A coward might be called a “chicken shit.” If someone is going to get mad, they’ll go apeshit (which I believe is one step below shitting a brick). More than once, I’ve heard dumb people called “dumb as dog shit,” though I always preferred “shit for brains.”
It can be both hotter and colder than shit. Good music is the shit, bad music is just shit. Other people’s things are always “shit.” When the shit hits the fan, you are in deep shit (perhaps up Shit Creek with a turd for a paddle). People can be bored as shit, hungry as shit, tired as shit or sure as shit. Something can be as funny as shit, slow as shit, fast as shit, hard as shit, soft as shit, scary as shit, cool as shit, broken as shit, quiet as shit, or loud as shit.
Frankly, there’s a literal shit-ton of uses for the word, and I think it doesn’t get the respect it deserves. As long as people keep “fuck” up on a pedestal, “shit” will always be #2.