He treats other people's trouble as entertainment.
Tips
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Colloquial / Beijing-flavored. The 子 suffix is unstressed (le-zi). Common chunks: 找乐子 ("find some fun"), 寻开心找乐子 ("goof off / amuse oneself"), 看乐子 ("watch a fun show" — often when something messy happens to others).
mistakes
Don't confuse 乐子 (fun) with 乐曲 (lèqǔ, a piece of music — 乐 here is yuè) or 落子 (luòzǐ, a chess move). The 乐 here is firmly lè (happy / fun).
