Smiles cost nothing so give them away! Apes can’t make any facial expressions like smiles and frowns. Remarkably our brain has the amazing ability to recognise subtle facial expressions very quickly. This is why we can find it hard to keep a straight face or to hide a guilty look.
When the boasting Apostle Peter denied that he knew Jesus, Jesus simply turned and looked at him and he burst into tears! The Bible says, “Be sure your sin will find you out.” [Numbers 32:23] It only takes a glance from God to make you feel guilty.