I am known as the guy in school who
A) Can make up nonsensical crap (Wales consists of a large volcano that spouts sheep) and sound genuine about it, even though EVERYONE knows it's just nonsense
B) Knows a crapbunch of trivia, and knows a load in intersting tidbits you've never heard before
By combining the two, I can, more often than not, lead people to believe a lot of silly things that JUST MIGHT sound plausible#
My sister has a massive tell (Ask her if she's done something incriminating (when she has) and she'll say NO, but then look at you as if she's exaspirated by your stupidity, and then smile stupidly and say "Whaaat?")
My brother dosen't really lie, but it's obvious when I've hit a nerve, because he stops being sarcastic. E.G.
"You're stupid" "Oh yeah, blatantly"
"You fancy her!" "NO I DON'T!!!"