Following is an example of the proper application of slut-shaming, in its purest sense:
Girl 1: I got so drunk last night, I don't even remember how many guys banged me!
Girl 2: Is that really something to be proud of?
Now, here's an example of an improper application of slut-shaming:
Girl 1: So last night, my boyfriend and I finally decided we were ready to go all the way.
Girl 2: He hasn't even proposed to you yet. You're such a filthy slut. You disgust me.
Note that Girl 1 is not actually a slut, but she is shamed as one, just because her sexual morals do not live up to an illogical and unreasonable ideal.
Here's an example of an even more inappropriate application:
Girl 1: I accepted a modeling gig for Playboy.
Girl 2: Oh gee, now the entire male half of the world's population can objectify you. Slut.
As in the last example, Girl 1 is being shamed as a slut for not living up to unreasonable standards of modesty. But in this case, she is not even having sex. She's being shamed for letting people look at her body.
This is an example of an absolutely gross misuse of slut-shaming:
Girl 1: I think these shorts will be much cooler in these hot summer temps.
Girl 2: You might as well flash your pussy to every guy that walks past. God, you're such a whore.
Now, Girl 1 is being shamed as a slut for her choice in fashion. But I'm very sorry to report, that it gets even worse.
Here is an example of the worst case scenario of slut-shaming, which is also referred to as victim-blaming:
Girl: I was raped!
Guy: Yeah, well it's your fault. You were asking for it, putting makeup on before you left your house, wearing that dress, being all sexually attractive, having two X chromosomes... I heard what you did with your boyfriend. You had no right refusing to fuck anyone else who wanted it, you big tease. You got what you deserve.