Nickname for DexCool, coolant used in later model GM vehicles. So named for its tendency to turn to sludge and clog your entire cooling system, eventually leading to total engine failure.
Deathonsteroid is more of a adjective than an everyday term. It can refer to the drug Death but with assorted steroid drugs, but most commonly means someone who can't figure out how to get good and gets stuck in low ranks.
Noun: Dude, try this deathonsteroid. When I took it, a dragon's ass came from Mars and blew up New York City.
Adjective: Lol, look at this kid playing Brawlhalla over here. 200 wins and he's stuck in Silver. What a deathonsteroid.
By definition, deathcore is a hybrid of metalcore and death metal. Deathcore bands typically sound like deathgrind bands with a heavy influence from modern metalcore with frequently used staccato, syncopated open-note breakdowns and metalcore screams. A vocal technique used in deathcore frequently is the pig-squeal, which is also used in other grind genres yet with a distinctively different sound to the technique. Bands such as Job For A Cowboy and Suicide Silence laid out the blueprints for the genre and spawned many other copycat bands. The Red Chord and a few other bands also helped to popularize the genre. Like metalcore and nu-metal, deathcore bands have received heavy criticism for supposed trendiness, lack of skill, and/or differences from "real" heavy metal bands/genres causing many bands to change to a pure death metal sound (Job For A Cowboy/Annotations Of An Autopsy) or a purely metalcore sound (Bring Me The Horizon).