Originally from a polite gamer sign-off ("enjoy the game"), it got shortened over time and repurposed to mean "forget it" or "get lost" — often used to shut down an absurd item-trade offer or dismiss someone outright.
A suffix shortened from "-grade student" — used as "yu-ding" (kindergartner), "cho-ding" (elementary schooler), "jung-ding" (middle schooler), "go-ding" (high schooler), "dae-ding" (college student), "jik-ding" (office worker). As youth crime has risen, harsher, more contemptuous versions aimed at middle/high schoolers have become more common than the plain forms.
It is spending small amounts of money within a range that does not interfere with daily life.
From the game World of Tanks — the Tiger tank had its engine mounted at the front, so hitting it there produced a distinct "bboo-riya!!" sound effect.
Represents flipping someone off — the middle finger, roughly equivalent to "f*** you."
A "geupsik-che" (teen internet speech) bit popularized by comedian Kwon Hyuk-soo on SNL Korea — a self-answered "agreed?" used to affirm something, playing on the title of a famous medical text (Donguibogam). Similar to "injeong? eoinjeong" (agreed? — agreed).
"Eye cleansing" — purifying your eyes, usually after "eye terror," by looking at something beautiful — gorgeous scenery, an attractive person, etc.
"Lust demon," shortened — invoked jokingly when someone's mind goes straight to something suggestive.