laugh out of court

court of public opinion

The news media and the public at large, seen as being able to deliver a judgement on someone in the manner of a judge.

enough to make a cat laugh

Very outlandish or outrageous.

have a laugh

To joke; kid around.

have the ball in one's court

Alternative form of the ball is in someone's court.

have the last laugh

To be vindicated; to triumph despite predicted failure; to find success after defeat or setback.

hold court

To serve as the principal discussant or center of attention in an informal gathering of friends, associates, etc.

kangaroo court

A judicial or quasi-judicial proceeding, or a group of people which conducts such proceedings, which is without proper authority, and often acts abusively or decides unjustly.

laugh a minute

A funny thing or person.