Here’s a joke that we’ve found on the web that features a lie detector robot at the hands of 3 people.
A father, son and mother.
Who’s lying and who’s telling the truth? You’ll find out 
A man returns from work with a lie detector robot. His 12 year old son comes home 3 hours late from schoo
This is a companion discussion topic for the original entry at https://community.robotshop.com/blog/show/joke-about-a-lie-detector-robot