in the 5th grade, I made a new friend, and probably literally the first day we really started talking and shit, he told me he was a vampire. he believed it with all his heart, kept a straight face about it and just rolled with it. I knew he was lying right away and I just went with it and said "You're a vampire too!?!?" and there was some sort of really crazy shit that we went along with for about a week or two until I think he finally got annoyed how everytime we were out in the sunlight and he would say "man, I don't feel so great" I would reply with "maybe it's the sun you know? we should probabyl get in the shade and hide". really ridiculous kid shit like that. he also told a plethora of other lies that included him being a ninja and dogs talking to him. the only time I knew when he was telling something true was when he said "you can even ask my mom". he still lies like this...but more "clever".
other than that little childhood memory, I have a few friends who can't resist telling lies here and there.