As a competitive FPS game, Team Fortress 2 has a domination system that encourages not just team-based competitiveness, but also a feud between two individuals of opposing teams. When a player has killed the same opponent four times in a row, it rewards a Domination for the aggressor. As for the victim, he will now see an icon over the dominator's head.
Once he finally kills him, the avenger will be rewarded a Revenge. On top of that, TF2 has implemented class-specific interactions with the domination system, adding some flavor to the feud. Upon dominating a player, the dominating class would scream out and taunt, thus adding insult to injury.
10 Rainbows
"May I borrow your earpiece? 'This is Scout! Rainbows make me cry! Over!'" - Spy to Scout
As charming and cunning as he is, the Spy has the most creative, the most insulting, and the most witted domination lines in the game. When dominating a Scout, the youngest class in TF2, he would take the Scout's earpiece and poorly impersonate him over the opposing team's comms.
Spy takes a huge jab to Scout's lack of manliness in this line, taking him for a unicorn-loving prepubescent. The poor satirical voice work makes this all the more hilarious as the Spy humiliates him to his team. Considering that the Spy regularly pays Scout's mom a 'visit' makes these interactions even better.
9 Hippo-Crates
"Where's your precious Hippo-Crates now?" - Scout to Medic
All the way from Boston, the Scout doesn't hold back with his insults. When dominating the class with the medical expertise, Scout takes the 'your mother' insult a step further. He takes a jab at the founder of medicine; Greek physician Hippocrates. Or at least-- he tries to. Pronunciation is key when mentioning Greek names. Especially well-known ones. In a futile attempt to say 'Hippocrates' (Hi-Pok-Ruh-Teez), Scout blunders all the way and says Hippo-Crates.
It won't be surprising if TF2 places Hippopotamus-themed hats inside Mann. Co supply crates but this doesn't excuse Scout's absolute lack of historical knowledge.
8 Kangaroo Wife
"I will send my condolences to your Kangaroo wife" - Soldier to Sniper
Soldier, the military guy, is filled with America, haircuts, and in this case, stereotype-level racism. As honorable as the Soldier is, he would sometimes insult the countries of non-American classes with a patriotic tone. With the Australian-raised Sniper, however, Soldier goes all the way.
He takes a whopping swing at the Sniper's Australian nature and background. Being the country known for its vast wildlife and love for animal preservation, Soldier's statements don't stray too far from the tree.
7 Where Are The Guns Going?
"Go on and build more o' yer little guns. I'll shove every one of them up yer arse" - Demoman to Engineer
The scotch-loving Demoman is filled with bellows of hard-hitting drunken insult. Being the explosive demolitions class, he is the hard counter to the Engineer. His best insults are also towards the Engineer. Sometimes, when dominating the Texan hard-hat, he wouldn't hold back on his deepest darkest thoughts as he screams exactly what he's going to do with the Engineer and his contraptions.
Though this may just be the alcohol talking, his hatred towards the toymaker could mean that with enough drunken force, he could definitely shove all his guns, moving parts included, up a certain narrow passageway.
6 Ugly
"And another thing: you're ugly" - Engineer to Heavy
A plain and simple insult. With his Sentry, the Engineer could dominate everyone within a disorganized team. However, his best insults are towards a class that has similar attributes to what the gunslingin' Texan has been wrangling -- cows. As a Texan, the Engineer makes many beef-related remarks on the fattest class in the game.
He would call him pork drippings, chuckwagon, corn cakes, fat man, fat boy, even say that he just got branded. But 'ugly' comes out on top. With this line, the Engineer literally adds insult to injury. Being majestic creatures, no herder would ever call a cow 'ugly'
5 Second Opinion
"Would you like a 2nd Opinion? You are also ugly!" - Medic
A doctor's second opinion is meant to advise the patient so he can arrive at a better conclusion. With the Medic, however, when all seems grim for his victims, he professionally gives his unbiased medical observation. In addition to performing poorly on the battlefield, his victims are also medically pronounced physically unattractive, and are hereby diagnosed with 'the ugly'
This domination line is screamed by the Medic when dominating members from the other team in general. This means that regardless of class, Medic has tendencies to say this to his dominated foes. And yes, that includes the Scout too.
4 Bugs The Sniper
"What's Up, Doc?! Heh heh heh!" - Sniper to Medic
Taking from the playbook of Looney Tunes' Bugs Bunny, the Sniper yells upon dominating the Medic "what's up doc?" The Sniper is a long-ranged assassin whose priority is to take out key classes on the battlefield. The Medic is one of the Sniper's prime targets since he keeps the whole opposing team alive.
Once the Sniper has killed him enough times, he busts out the iconic line, and yells it all the way from the back of his team. This is followed by laughter as the Sniper shows amusement in his own wisecrack.
3 Spy: 1; Demoman : 0
"Here's what I have that you don't: a functioning liver, depth perception, and a pulse!" - Spy to Demoman
The Spy delivers three huge jabs to the intoxicated one-eyed Scotsman. Upon dominating the demolitions expert, the Spy lists three key things that he, a healthy functioning human being, has that the Demoman doesn't. All of which are enormous insults to the Demoman's well-being.
A functioning liver is what anyone who values moderation has. Depth perception is what anyone with two eyes has. And to top it off, a pulse is what anyone who isn't dead has. Spy says this after he's killed and dominated the Demoman; making it an amazing cherry-on-top of a perfect backstab.
2 Hard Arteries
"Hey, lard-fat, those hard arteries don't stop bullets do they?" - Scout to Heavy
The Scout and the Heavy are exact opposites. Scout is a fast-moving small class, while Heavy is a big slow class. Scout takes a lot of jabs at Heavy's possible diabetes, his size, his massive gun, and even tauntingly advises him to eat a salad. In this domination line, it's bad enough that Scout calls the Heavy 'lard-fat'
He then makes fun of a possible Atherosclerosis in the Heavy, referring to all the built-up fat inside of him. After killing him, Scout remarks that no matter how hard and clogged Heavy's arteries get, they can't ever stop bullets.
1 Bra-Washer
"That's a right pretty bra-washer ya built, ya big ugly girl!" - Demoman to Engineer
Demoman will never get tired of insulting the Texan toymaker each time he throws a wrench into his plans. The drunken one-eyed Scotsman takes a jab at the Engineer's playstyle, attributing his reliance on his buildings to an absence of masculinity and courage.
The valiant swordsman pokes fun at the non-manly nature of the Engineer and does the same for his buildings too; calling the Texan gunslinger a 'big ugly girl', and condescending on the 'pretty bra-washer' he built.