expression, noun-modifying (irregular)
Prenominal expression meaning something is so absurd or foolish that it deserves laughter or mockery. Often used in the pattern 笑うべき話 (a laughable story) or 笑うべき間違い (a ridiculous mistake).
That's a laughable mistake.
His excuse was ridiculous.
Standard kanji spelling using 笑う (to laugh).
Rare kanji variant using 嗤う (to sneer/laugh scornfully); adds a nuance of derision.
Formed from the verb 笑う (to laugh) + the classical auxiliary adjective べき (should), functioning as a prenominal modifier meaning 'should be laughed at.'