Lie Detector prank

Is someone cheating on you? Does he lie frequently?
Now we have this cool prank app to fool your family and friends.
Simply put your finger to the fingerprint scanner and wait couple of seconds for the answer.
This is of course joke and prank, but you can use it to check other people for fun.
Ask the question and make them touch the scanner. Then wait for answer.

This app also includes some trick to force given answer. In general it gives random answer, but
you can force particular answer with small trick. To make it result always truth - touch the display
one time before testing finger. To make it result lie - touch the display two times before making a test.