I used this object lesson to teach about hypocrisy to my Seminary class. First, I printed chewing gum inserts on card stock. Each insert was 140mm x 18mm and fit inside a Juicy Fruit wrapper. On each was written the following references and words: "Thou Whited Wall" Acts 23:3 and "Full of Dead Men's Bones" Matthew 23:27.
After cutting them out, I put the "fake" gum in the center section of my gum box so I could keep them straight.
While teaching the class about the Apostle Paul's appearance before Ananias and the Sanhedrin in Acts 23, I stopped just before Paul called Ananias a "whited wall". I asked the kids if they wanted any gum to help them stay awake. Some said yes, and I gave some untouched gum and to others I gave gum with the handout inside. Once the students realized that they had been gypped, I asked them why it was a problem that the gum was different on the inside than the outside indicated. It's hypocritical. We say one thing, and do another. We talk the talk, but we don't walk the walk. We read the scriptures on the handout, and talked about how outside the Pharisees looked good, but inside they were spiritually dead, or "full of dead men's bones". We cross-referenced with 1 Samuel 16:7 ( a scripture mastery!) to talk about how God looks on men's hearts and not on their outward appearance. How should we treat others?
For your information, the phrase "whited wall" could be termed whitewashed wall, meaning a thin veneer of paint put on something to cover up the ugliness beneath.