Quotes / Cannot Tell a Lie

Black Mage: Telling the truth isn't a speech impediment!
Red Mage: But it kind of is with us.

Truthful, adj: dumb and illiterate
Ambrose Bierce, The Devil's Dictionary

The Doctor: I'm the Doctor. I'm a Time Lord from the planet Gallifrey. I stole a time machine and ran away and I've been flouting the principal law of my own people ever since. That wasn't quite what I meant to say!
Clara: I'm an English teacher from planet Earth, and I've run off with a man from space because I really fancy— [claps hand over mouth]
Marta: I think, perhaps, you should stop talking till you get used to it.
The Doctor: Used to what?
Marta: What did you say your name was?
Clara: Bubbly personality masking bossy control freak.
The Doctor: I'm wearing a wig! No, ah, I see. Yes, of course. It's a truth field. Oh, that is so quaint. I haven't seen a truth field in years. I'm wearing a wig.

http://tvtropes.org/pmwiki/pmwiki.php/Quotes/CanNotTellALie