"You canker blossom!" 3 Shakespearean Insults
mid-13c., not in Old English, from Old Norse klaka "to chatter," of echoic origin; cf. Dutch klakken "to clack, crack," Old High German kleken, French claquer "to clap, crack (see claque). Related: Clacked; clacking.
mid-15c., from clack (v.).