Here is a great idea we used last night from the Proverbs: Family Night Tool Chest.
In order to show a good lesson and have a good family discussion on the consequences of lying, have each family member put a small pebble in their shoe. Then have them go outside and walk around. Then, give each person a spoon with a hard egg. Mark start and finish lines and have family members race with their eggs. (You will probably hear some groans as they race!)
Then go inside and read the following Scriptures together: Exodus 20:16, Proverbs 6:16-19; 11:1; 12:13.
Talk with family members about how a web of lies can become like the pebble in the shoe. We can't outrun our lies, they cause pain for ourselves and eventually other people. And they will eventually cause other people to stop trusting us.
We tied our discussion to the actions of Gehazi, Elisha's helper, in 2 Kings 5, and talked about the negative consequences of greed, deception, and dishonesty.