joke

be no joke be a serious matter or difficult undertaking. informal

2014Telegraph The police already have access to much more violent means of crowd control. If you look at a baton round, it's no joke if you get that in the eye.

get (or be) beyond a joke become (or be) something that is serious or worrying. informal

2002Guardian The rogue animal is believed to have attacked at least six residents in the past week, and his antics are now described by residents as 'well beyond a joke'.

the joke is on someone someone looks foolish, especially after trying to make someone else look so. informal

2011New York Times It's terrifying to realize that this kind of cynical careerism … has probably ensured that we won't do anything about climate change until catastrophe is already upon us. So on second thought, I was wrong when I said that the joke was on the G.O.P.; actually, the joke is on the human race.