Cuts caper is an idiom that means to play a prank or to behave in a lively or mischievous manner. The antonyms for this idiom would be to behave seriously, to be grave or dull, and to be somber or earnest. Other words that could be considered as antonyms for cuts caper are to conform, to comply, or to adhere to the norms or standards of society. In some situations, being well-behaved or disciplined could also be considered as an antonym for cuts caper. Therefore, the context of the situation would determine the appropriate antonym for cuts caper.