(informal)be a serious matter or difficult undertaking
(非正式)严肃的事；不轻松的事；困难的事
trying to shop with three children in tow is no joke.
要带着三个孩子去买东西可不是件轻松的事。
(informal)become (or be) something that is serious or worrying
(非正式)（变成）严肃的事，令人担心的事
this rain's getting beyond a joke.
这场雨越来越让人担心了。
laugh or be humorous about (something that is not funny in itself)
对（并不好笑的事）以笑（或幽默地）对待，一笑置之