There aren't that many, and of course this is more for entertainment. I will start it out
1. You didn't post a complete, working example to a homework problem that can be copied, pasted, and handed in.

Because I've offended someone who is still in a deep-seated denial of the fact that their opinions are necessarily wrong whenever they are opposite to mine, because I'm always right. ;)

Your code is so bad, my eyes are bleeding.

You've caught me out cheating and spanked my bum in public

I don't care about no stinkin' down vote. I have 10 email addresses. I'll cancel your single puny down vote and raise you 9 up votes.

In the Python forum you get down-votes because your solution works in version Python3 and not in the old Python2 version. What a mess that is.

you downvoted me once
so i am going to find every post you made and downvote it

people who can't stand the truth tend to downvote those who tell them the truth...

There is a difference between saying "you are a ####ing moron" and saying "that turns out not to be the case". Both may be true but the former will get you downvoted and the latter will probably not.

There are times when I try to be polite.

i've heard that word before
whats a polite?

Polite comes from Latin politus ('polished'), so a polite is a polished person.

A polite is also a person that has never ever downvoted almostbob.

I was downvoted (a number of times) once because the person had the next reasoning in mind:

"You have the nerve to point out that my replies are dead wrong, the code I provide is not what is asked for, nor should be provided, and my advice can only confuse the person who asked the question ? Such insolence ! I'll downvote every single post of yours I can find within the next half hour !! " :p

"How dare you have a blue guru button, just because everybody else thinks your right, I'll get you."

Once more: "How dare you have a blue guru button, just because everybody else thinks you're right, I'll get you."

the horrible spelling downvote
and the guru downvote