How to spot a liar?

So I was in my happy-go-lucky mood again in the office the other day.

As I was busy singing, dancing and moving out to the pantry with Mars, Dr.House Wannabe Arthur asked me a question which I answered briefly (while scratching my ear).

"Do you know how to spot a person lying?" he then asked.
"How?", I briefly answered again
"Just like kids, you can spot a person lying/guilty when they talk while scratching their ear or nose or head"
"Oh reaaallllyyy??"
"Yes..REALLY"
"Owhhh... WOW...you look SO GOOD today Arthur ", I said while scratching my ear.
"Yeah.. SOOO COOL and HANDSOME", Mars continued + trying to dig her nose.
"pfft... "

.