"I have read the terms & conditions & I agree to them."
Everyone lies. You do, your friends do, your parents do, if there was a God, I'm sure he'd tick the terms and conditions box without actually reading them. Of course, there's a certain psychology involved behind that.
No one would fill a massive form and then end up not agreeing to the terms and conditions. You know the terms and conditions are important but the form you've just filled is more often than not provided by a sort of big shot company or person and you know that they won't try to trick you and have stuff written in the terms and conditions which might land you in prison for using their service. Equally, you know you are a good person, even if you're not, you believe you are a good person and won't take advantages of their said terms and conditions and break the law, so might as well tick the box rather than read that 12 page form.
That is one utterly pointless lie that all of us would have said at some point or the other in our lives. However, that is something commonly known as a white lie. A lie that might not have any serious repercussions.
There are other similar lies that 93% of the population says at some point or the other and make very very similar gestures to give away the fact that they're lying.
But this is a lie which we are actually nervous of while telling it. So the sentence is usually accompanied by your hand being raised to a part of your face. Either to scratch your nose, rub your ear, touch a part of the forehead or something along those lines. Why do we this movement? Simply because when we lie, there's this awkward silence when no one is saying a word. We feel that silence because we are the ones who are lying and are nervous, however, the person we are lying to will NOT feel that silence most of the times, unless we shows signs of nervousness by doing one of the actions mentioned above.
There will be times when you're telling a serious lie, could be anything and to anyone, to a friend or family, you'll notice your breathing rate increases and when that happens obviously your chest begins to heave. If you think someone's lying to you, this could be another way to figure out. Just stare at their chests, and risk being considered as a creep.
Also, just so you know, the people who lie the best are the ones who continue talking non stop. And can tell a tail as it happened and can also recollect the events that supposedly occurred in reverse order. Every liar practices a story, no one practices it in reverse.
And yes, I HAVE read the terms & conditions once in my life. Just so you know, they're utterly pointless.