Noun
wicked tongue (plural wicked tongues)
(idiomatic) An abusive, vulgar, nasty, or otherwise objectionable manner of speaking.
The thing that made Groucho special was the way he used his body parts. He also had a wicked tongue. People didn't realize it, but when Groucho said something, he meant it. Sidney Sheldon
What are you doing?" she asked, trying to raise herself. "First, I thought I'd show you what a pity it would be if they cut off my wicked tongue. Melina Marchetta