I was once told that the tongue is very light weight and so to commit haram with it is very easy.
Besides lying there are also some of the haraam acts that could be done – in summary they are all hurting someone’s feelings using the tongue:
– Abusive Language
A little about the last two:
•Teen 1: Oh, here comes that cannonball guy. He’s cool.
Teen 2: Are you being sarcastic, dude?
Teen 1: I don’t even know anymore.
(“Homerpalooza,” The Simpsons)
Sarcasm explained very well:
•”First, situations may be ironic, but only people can be sarcastic. Second, people may be unintentionally ironic, but sarcasm requires intention. What is essential to sarcasm is that it is overt irony intentionally used by the speaker as a form of verbal aggression.”
(John Haiman, Talk Is Cheap: Sarcasm, Alienation, and the Evolution of Language. Oxford Univ. Press, 1998)
Impertinence Meaning : Rude and disrespectful