不亦樂乎

不亦乐乎
bùyìlèhū
  1. lit. isn't that a joy? (quote from Confucius)
  2. fig. (jocular) extremely; awfully

CEDICT

jocular

Entry Composition

1 不亦 bùyì (literary) isn't it truly …?; how … it is!
2 樂 lè
  1. happy
  2. cheerful
  3. to laugh
3 乎 hū
  1. (classical particle similar to 於 yú) in
  2. at
  3. from
  4. because
  5. than
  6. (classical final particle similar to 嗎 ma, 吧 ba, 呢 ne, expressing question, doubt or astonishment)