Played a shitton of Gears of War 1 back in the day by which I mean glitching the absolute living fuck out of it because hoo boy did people get mad. What made Gears 1 a great (bad) game is that there was like 20 different easy-to-pull-off glitches and you could just ruin matches at will with just a single one.
There was the simple chainsaw glitch which allowed you to move immediately after chainsawing somebody (once got 3 people in a row with it) crabwalking, which allowed your character to aim and shoot while sprinting which combined with a weird-ass animation made you hard to hit. My personal favorite was a different chainsaw glitch wherein you essentially turned a different weapon (other gun, grenades or pistol) into a chainsaw and by touching an enemy with it you'd do the animation but they wouldn't disintegrate until either you switched to your lancer again or died. There was nothing more fun than doing it in a 1-on-1 than running around the map until the clock dropped to one second left and then gibbing the guy from halfway across the map. And then finally you had your bread-and-butter match ruining kung-fu flip which allowed you to jump either out of bounds or into the map itself which would lead to a variety of different results. Most times at least one person (sometimes host) would just immediately quit, sometimes they'd try and rush you hoping they could stop you before you did it the next round (which rarely worked) and then sometimes one or more people on the other team would flip out of the map too either landing immediately into your chainsaw (like when you're in the pillar on War Machine) or turning matches into long, drawn-out games of hide and seek where you could hide behind a wall and watch player or players running around desperately trying to figure out where you are before time runs out and they have to do it again as more and more people get fed up and quit and the game stretches past an hour tied 0-0.
Since these were the days when people could say and send whatever they wanted with absolutely no worries they'd end up getting exposed on Twitter or in some Kotaku article that meant drowning in glorious, glorious hate mail, "my dad works at Xbox and you're fucked!" and more death threats than one could possibly count. Boy those were some fun times.