How could you recognize if the person is telling the truth or not?

yup, i don't think you should tell him that you know he's lying. He will just feel that you're not fun. just hear and laugh and everything will be okay.. just keep it in your mind that you know the truth, that's enough..

I had a friend like that who was not really "lying" but she embellished a lot. She would add a few facts here and there so make the story more interesting. Some people are entertainers and they like to tell stories. I think you would offend your friend if you come right out and say "I think you're lying". You can just know that they are lying but don't bring it up to them because that could cause problems. I also saw this show on television that shows when people are lying they look to the left because that's the creative side of your brain. I don't know how true it is but it's a possibility.