you/he/she must be joking

:  the one or ones being addressed — compare thee, thou, ye, your, yours

:  one

:  that male one who is neither speaker nor hearer — compare him, his, it, she, they

: used in a generic sense or when the sex of the person is unspecified

:  a male person or animal

:  that female one who is neither speaker nor hearer — compare he, her, hers, it, they

: used to refer to one regarded as feminine (as by personification)

: used as an alternative to he to refer to a person of unspecified gender

:  be commanded or requested to

:  be urged to :  ought by all means to

:  be compelled by physical necessity to :  be required by immediate or future need or purpose to

:  an imperative need or duty :  requirement

:  an indispensable item :  essential

:  the expressed juice of fruit and especially grapes before and during fermentation

:  the pulp and skins of the crushed grapes

:  musk

:  mold, mustiness

:  something said or done to provoke laughter

:  a brief oral narrative with a climactic humorous twist

:  the humorous or ridiculous element in something

:  to make jokes :  jest

:  to make the object of a joke :  kid