Hugest

Hugest
 

When John hears a ridiculous thing, can he say this?:

-This is the hugest joke I've ever heard in my life.

Yes, but a ridiculous thing isn't always equated to a joke.

Thank you~

Then what would be those natural English expressions used by a native speaker?

That's the most ridiculous thing I've ever heard (in my life). (anything that seems preposterous or absurd)

The biggest joke ever played on someone else was ... (a prank/a practical joke)

I just heard the funniest joke ever. (a humorous story/quip)

Thank you~