wicked tongue

Noun

 * 1)  An abusive, vulgar, nasty, or otherwise objectionable manner of speaking.
 * 2) * c. 1870, Geoffrey Chaucer (original), David Laing Purves (modern translation), The Canterbury Tales, The Manciple's Tale:
 * My son, keep well thy tongue, and keep thy friend;
 * A wicked tongue is worse than is a fiend