hera-hera
Laughing or smiling in a silly, thoughtless way — often at an inappropriate time. It comes across as not taking things seriously.
💡Getting scolded but just grinning — 'He was hera-hera even though the boss was furious.'
怒られているのにへらへらしている。
He's grinning hera-hera even though he's being scolded.
He was ___ during the serious discussion, which annoyed everyone.
真剣な話し合いの最中に○○していて、みんな呆れた。