Meaning of "joke" in Essential American English Dictionary

joke

verb us /dʒoʊk/ (present participle joking, past tense and past participle joked)

B1 to say funny things, or not be serious:

She always jokes about her husband’s cooking.
you must be joking! informal

B1 used to say that something is certainly not true:

“Does Jim do much cooking?” “You must be joking – he never cooks!”

(Definition of “joke verb” from the Webster's Essential Mini Dictionary © Cambridge University Press)