Bear in mind that sometimes the internet is not that reliable in some countries so disconnecting is not their choice but yes some of those points are valid.
10,000 Ways To Piss Off Your Online Blitz Opponent
You're supposed to list some things that triggered yourself to go all haywire or that made your opponent rage
12) typing IOwNZUuuuuuu over and over again after winning might be one of them
i will use that
Mine is 13). Saying PWN3D your PAWNS over ond over when you capture pawns.
14). Asking them "guess what came in the mail today?" as in Deez Nuts over and over.
15) Saying "that's what she said" whenever they say say something.
16) Telling them to go frick themself.
17) Telling them to go frack themself.
18)Telling them to go frig themself.
19) Telling them to go fug themself.
20) Saying that you have to take a "dump", "whizz",or "leak", or saying that you have to shed waterload every 2 miniutes

1) Lagging
2) Disconnecting and reconnecting
3) Abandoning the game
4) Typing 'hi', 'gl' or similar at the start of a game
5) Typing 'gg' before the game is finished
6) Typing 'gg' after you've won or lost
7) Disabling chat
8) Asking for a rematch or declining a rematch
9) Playing on trying to flag when down a piece
10) Taking a perpetual check when down material
...and 9,990 more!