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.
A suffix meaning "there's a strong chance of / it looks like it's about to happen," e.g. "injeong-gak" ("looks like it's confirmed").
It originated from the fact that speaking "father-in-law" quickly sounds like "shap-jwi." It is a casual term used to refer to a father-in-law.
"The top dog" in a given field, similar in meaning to "jonggyeoljja" (the finisher). Traces to a photo of a KIA Tigers fan holding a sign that misspelled the character for "god" (神) as a similar-looking character (申), which someone else then further misread as yet another similar character, 甲 (meaning "first/superior"), giving rise to this usage.
"Strongly recommend," shortened. The opposite, "don't recommend," is shortened to "bichu."
It is spending small amounts of money within a range that does not interfere with daily life.
"If I'm satisfied, I'll open my wallet" — buying based on personal satisfaction rather than price/performance value.