Wait

I would say it can be both. Anger causes people to speak against their better judgement. How one person deals with anger can be completely different to another. There may be some truth to what people say out of anger but it's likely exaggerated.
How many people lose their temper and tell their friends or family members they hate them? A comment that might be true in some cases but not in most.

I should add that the above meme was not an attack on you just in case the sarcasm wasn't obvious :)

OP, THAT post was the sarcasm, not the first. Timidy is crafty.

When someone gets extremely angry, their brain no longer thinks properly.

Depends. Sometimes when angry we let our inhibitions go and whatever is on the tip of our tongue spews out unfiltered. On the other hand, sometimes we say things we know to be skewed or untrue or false or just mean because we know it will get under someone's skin. Ask any married couple or couple that has dated for an extended period of time, they will be able to tell you every button to push to infuriate the other. Maturity comes into play here, and truly mature or relationship savvy people will say that it's best to know those buttons but never push them, even if you are tempted to do so. Anger gets the best of us though, and sometimes it just comes out that way. Forgiveness is a powerful tool though, and should be used liberally :)

um from what i say no

From my experience (and I have a LOT of experience), no.
When someone is angry, they tend to stop thinking logically and get carried away by their emotions.

I have had to not speak when extremely angry. My ability to snark goes too far and could cause lasting damage to people I’m mad at right then, but only then.

It's best I didn't say

It is honest to say what ya think. As to whether what you think is refined, good, right, or smart.. that depends on how much personal growth you've actually accomplished in True Self. You could let unfounded emo word salad out in anger.. or you could let out things you really know.. or things you think in bad judgment.. or irrational things.. Free associating ideas is splatter art.

i once said something like "this game makes me want to kill everyone including myself". i say that when im super triggered about a game in P.E. Anger makes me say suicidal things and cuss words. I don't ever mean anything that I say when I'm angry, so in some cases, the things that people say when they are angry are not actually meant to be said. They just say them because they're super triggered. Some people, though, might actually mean these things. It depends on the type of person and how they react.