哑然失笑

Explanation: Laughing can not help but laugh. Could not help but laugh. 　　Usage: Partial official; as predicate, attributive, adverbial; that could not help but laugh 　　Source: Han Zhao Ye, "Annals of Wu and Yue Wu Yu rumored" Yu is a dumb but funny. " 　　Examples: Wang Zian inch into the instant million threads, like a ghost laughing fox has long, so catch them while playing the drunk, who wake up the bed, rather not ~ zai. ★ Qing Pu "Liao Wang Zian" Thesaurus:  be dissolved in [into] tears, cannot help laughing, Renjunbuzhu, let loose a banquet of brine, tears and mucus flowing down rapidly, naturally, Spontaneously, quiet or partly suppressed laugh Antonym Group:  forced laughter, find happiness in suffering