BEIJING, Aug. 19 -- One improvised lyric has landed one of China's biggest comedians in decidedly unfunny territory.

Guo Degang, the household-name performer credited with reviving traditional Chinese crosstalk comedy, is under investigation after altering the words of a well-known revolutionary song during a performance in Wuhan last month, CNN reported.

Some performances on Guo's nationwide tour have since been cancelled as authorities examine whether his unscripted gag breached China's rules governing commercial performances.

The controversy centres on Playing My Beloved Pipa, a song associated with communist guerrillas fighting Japanese forces during the Sino-Japanese War and featured in the 1950s film Railroad Guerrillas. In 2019,...