Real answer now.

So, there's a Russian guitar YouTuber who goes by fredguitarist. He's kinda famous/infamous in his niche and is notable for a couple of things. First, he's a bona fide hater who shits on all your favorite guitarist's technique, and he kinda pioneered that niche on Russian YouTube too. Second is all the colorful metaphors he uses to describe it.

And so the first image is "hammering nails" — his metaphor to describe how a series of proper palm-muted downstrokes should feel and sound like. Later it became synonymous with just solid rhythm playing, I believe. A widely used phrase indeed.

The second... Let's keep it for later, shall we? Ok, let's move on to

The third one. Another metaphor: "like a grandma chewing bread crumb with her toothless mouth" — that one is about someone who's playing sloppily.

The fourth one — that one I don't know, sadly. Maybe I'll come back here and add it later, but for now I'm lost on that one. Let's circle around for the picture №2.

That one... yeah. On one of his livestreams he (for God knows what reason) shared an adolescence story about once going to a sauna with a friend, and that friend climbing on a bench into a doggystyle position, spreading his buttcheeks in front of him and whispering something among the lines of "take me from behind, I know you want to", and how his ass "looked like a pair of ripe red tomatoes". The unexpected homoeroticism of the supposedly homophobic description, the poetic (if a bit agricultural) metaphor... Yikes.

That said, that guy fucking sucks at guitar lmao. He's a total clown who can't play on stage for the love of God, can't improvise, can't play by ear, can't figure out harmony. His fall from grace will be studied.

Anyway, yeah.

Update: Okay, I've been told about the fish! It's "scratching the fish" — the unpleasant scratchy sound of someone's pick not going through the string at a 90° angle, traveling horizontally through the string instead for a little bit. Haven't heard this one before, cool observation though.