WARNING: I DO NOT ENDORSE OR RECCOMEND YOU DO ANY OF THESE THINGS TO INTENTINALLY ANGER THE ENTIRE TF2 COMMUNITY. THIS POST IS MOSTLY A JOKE AND IS A WAY FOR ME TO BASH AND PARODY THE PEOPLE WHO ACTUALLY DO THIS CRAP. THANK YOU FOR UNDERSTANDING AND HAVE A GREAT DAY.
:)

Scout is very simple all you need is all lime cosmetics, a lennyface bind you can spam after every kill, and some decent amount of skill as scout, or aimbot hacks/silent aim if you are a horrible person who is terrible at FPS games. dont use hax grind it out yourself you moron. the best limescout loadout is generally a war paint reskind of stock scattergun, mad milk/pretty boy's pocket pistol, and atomizer or some random melee.

there's a lot of ways tp anger people as soldier. but generally you can have a decent amount of skill, be a tryhard with a medic GF and any loadout. ...OR you can also use the black box/direct hit, concheror, and escape plan. or if you really wanna flex your skill at the game and anger noobs and tryhards while still having a goofy fun reputation, learn trolldier. Trolldier is the only subclass I will be covering in this guide. all you need is any rocket launcher, gunboats/manntreads, and the market gardener.

I'm a pyro main myself so this one is easy. its:

Have any decent amount of skill as pyro and use any loadout you want. people hate you anyway. people will bully you, harass you, and berate you for playing pyro with any flamethrower or strategy in your arsenal. the only exception is landing good flares because those are quite hard to pull off and most cultured players will respect you for it. OTHER THAN THAT, people hate pyro for barely any reason unless they know that pyro's source code is absolute garbage and needs a total redo, which is fair because making workshop weapons for pyro that are flamethrowers is absolute doodoo to work with. pyro gets a lot of uncalled for hate outside of that imo.

Demoman is also a bit of a really hated class. all you need is the stock stickybomb launcher or quickie-bomb launcher, some crits, and the know how to spam MOUSE1 and MOUSE2 at a choke. some people also hate demoknight but he's a whole new can of worms. standard demo with some certain sticky launchers and grenade launchers can be an absolute pain to deal with. not to mention a pocket medic or if he's spawncamping.

Heavy is simple man, heaby is simple to make everyone hate you. be a toxic tryhard with a pocket medic GF. just W+M1 more brainlessly than pyro with a pocket med and boom you insta win because "tHaT'Z HoW tF2 WuRkZZZZZZ". in all seriousness please dont do this heavy is already a hard class to deal with, man's a tank.

Engineer has many ways of making people hate him, annoying sentry placements, sneaky teleporters, spawncamps, turtling, defending, gunslinger, he's really good and nice to his team, but to the enemy, he can be like hell. I reccomend not giving engineer more reasons to be hated on by creating lime-engie.

not a lot of ways to piss people off as medic, he's just support. though some people hate medic for just existing due to the fact that a competent and good medic can help his team so well that the enemy just gets absolutely thrashed. medic is generally played by nice people who want to help, or battle medics. normal support players are beloved by their teams. battle meds? not so much. but they still do a fair amount of healing, even if its minimal.

people REALLY ♥♥♥♥♥♥♥ HATE SNIPER. kinda like pyro. this has just worsened by the bot crisis. the entire class of sniper is hated. every item in his arsenal to the average non-sniper player thinks all his weapons are OP if used properly. not always the case. though it can be true, just look at the huntsman, the machina (used by a great sniper), Sydney sleeper, the bazaar bargain or even the stock sniper rifle. minimal effort is needed to use sniper. just click on heads and have really good aim, and paitience. not everyone has these things tho. somehow a demoknight is a great counter to hard-scoping snipers.

how to make people hate you even more? well just wear an edgy cosmetic loadout, taunt after every kill, spam crappy binds, or just use aimbot blatantly. if you wanna be annoying you can just play sniper. tho it is a bit sad tosee people hate snipers by default as soon as they enter a server.

spy is also really easy to piss people off as. all you need is the ambassador/diamondback, dead ringer, and any knife that isn't the stock knife, but most common used is the kunai. hell sometimes you can even have a different loadout entirely except for observer spy and people will hate you. spy has insta kill backstabs that are really hard to counter.... just kidding. TURN AROUND. spy is countered by COMMON SENSE. he's a crappy class that needs a full rework or a new playstyle. spy is mostly played by tryhard kunai sweats anyway. thats why he has a horrible rep. the only common spy players you see are slaves to the spy meta, its the only reliable way of getting kills as him, even if its annoying as hell.