I was playing a game and I think my opponent was cheating

Ok so the game started out as normal. It was a typical four knights opening or whatever, and after we exchange a few pieces, my opponent all of the sudden has a third knight on the board? After seeing his knight appear out of nowhere, forking my queen and king, I got really mad, since I just lost my queen to a cheater. Then, he somehow got a second queen without even promoting a pawn? How is that possible! He has to be a hacker. Anyways, he checkmated me shortly after, and I reported him and swore at him for cheating. Can you believe this happened?

Like, the pieces just appeared randomly on the board. I didn't know you could cheat like that on computer! Insane!

You haven't played anything like this from your account - maybe forgetting to log in? Nevertheless, congratulations for playing unknowingly the variant named crazyhouse, where such situations are perfectly legal. Returning to normal chess, abandon this ...f5 ...g5 black setup, please, unless your aim is to lose as much and as quickly as possible.

what is crazy house? and what is so bad about ...f5 ...g5 opening for black and f5... g5... opening for white?

Google is your friend. For example, you have a good explanation here: lichess.org/variant/crazyhouse. As for the opening, it does nothing towards the development of your pieces and very dangerously exposes the king. In the other thread you copypasted quite a bunch of pieces of advice for weak players - but did you bother to read them first?

Oh, sorry, correction. You didn't post them, the other person did. You only complained there are too much of them.

i'm a philosopher

You can do that if it's crazyhouse, but if not, he is a hacker or maybe it was a glitch.

again I don't know what a crazy house is. I was just playing chess and then he places a bunched of pieces down. I think he is a hacker I forgot his username

Excuse me, being a philosopher doesn't seem to impair reading abilities, does it? In my previous post I gave you a link with clear explanation of the crazyhouse rules. To write it as short as possible: there exist many variants of chess, much less popular than the original game, differing by some rules. You agree to play the aforementioned one, named crazyhouse, by clicking on the game offer with big H picture. Then you may put the partner's captured pieces back on board as yours. Stop seeing hackers everywhere, as it makes a fairly pathetic impression.