riajuu リア充

In Japanese, riajuu リア充 means "normie," basically. In the same sense weebs would call people normies. It's a word used by losers otaku オタク to refer to someone who, unlike them, is leading a fulfilling life: they have friends, a girlfriend, good grades, a good job, money, social skills, they go the beach, travel, and so on.

Literally, riajuu リア充 is the abbreviation of riaru リアル, which means "real," as in not the virtual, internet world, or the fantasy 2D anime-land, In Real Life, or Outside™, and the word juujitsu 充実, which means to be "full" or "complete," as opposed of lacking somehow.

• riaru ga juujitsu shiteiru
  リアルが充実している
  Real is being full. Complete.
• Someone feels fulfillment for their real life.
• riajuu me リア充め！
  [You damn] riajuu!
  [You damn] normie!
• Used when a someone is envious of a riajuu.

The antonym of riajuu リア充 is hiriajuu 非リア充. Other, practically synonym terms are:

• kachigumi 勝ち組
  Winning group. (i.e. winners at life.)
• makegumi 負け組
  Losing group. (i.e. losers.)

Another word is netojuu ネト充, which means your internet life is fulfilling, rather than your real life.