Mocking the position

This is something I've come across many times, though I'm not sure it's a fallacy or just an unscrupulous debate tactic. I don't really think it's an appeal to ridicule, as that involves exaggerating an argument beyond reason.

Basically, instead of giving an counterargument or defense to a claim/argument, the opposition simply laughs at/mocks the arguer's position in order to diminish it's validity.

Some examples:

"You clearly don't clean around the house, seeing as I left this house for a week and came back to an absolute pigsty."

"Yeah sure, I never do anything at all, you're totally not whinging right now!"

"Your performance at work goes down when you drink. You've started drinking again, and immediately your performance started to suffer."

"Yeah of course it's the drinking, you're so right, aren't I just a slacker hahaha"

Similarly, I also recently saw some well-known internet personalities being accused of slacking off on work in order to further a business venture, and they replied, not with a defense/explanation, but by simply mocking their fans for noticing it at all.

Basically, the opponent is not giving a counterargument to the claim, he/she just derisively mocks the position, and by extension, the arguer. What would you say this is?

Not an argument. It's rhetoric; often sarcastic, but sometimes just directly insulting.

Now, if the second person insults the first person (and uses that to dismiss their claim), it is now fallacious (ad hominem (abusive)).

For instance:

Joan: I really think your performance at work is affected by the amount you drink.

Jasper: Well I think you're stupid, so it can't be anything to do with that.

This is a non-fallacious example, similar to the one you gave:

Joan: Honestly, you shouldn't drink so much; it's probably getting in the way of your work.

Jasper: Yeah, SURE. It couldn't be anything else, right?

This is called "Passive Aggressive Behavior". 
Passive-aggressive behavior is a pattern of indirectly expressing negative feelings instead of openly addressing them.
https://www.mayoclinic.org/healthy-lifestyle/adult-health/expert-answers/passive-aggressive-behavior/faq-20057901

Also,
"Passive-aggressive means that we don't say what we mean but rather we say something positive but we say it with an angry tone or angry feeling underneath."
https://www.youtube.com/watch?v=5nWSBZxRkA4

So, it's not an argument. It's indirectly expressing disapproval or dismissing of what the other person claims. Sarcasm, I guess, would be another name to describe it.