What does this idiom mean: "to play the goat"?

[Kasia]

English Idioms and Expressions, Elementary Level

ESL/EFL Test #9 "Animal Idioms", question 7

Until he is more serious in his job and stops playing the goat, he won't get any more money.

(a) arriving late all the time
(b) eating too much all the time
(c) making too much noise all the time
(d) making jokes all the time

English Idioms and Expressions, Elementary Level

ESL/EFL Test #9 "Animal Idioms", answer 7

Until he is more serious in his job and stops making jokes all the time, he won't get any more money.

Correct answer: (d) making jokes all the time
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Could you explain me the meaning of "playing the goat" Thank you !

Kasia

[Conchita]

Apart from the definition given in the test answer: 'making jokes all the time', another meaning of 'playing the goat' is 'behaving foolishly'. 'Acting the (giddy) goat' is a variant expression.