Before starting Family Night, and without anyone seeing, wrap a book of Mormon in something special (wrapping paper or a special bag, etc). Then put it out on the porch. After the song and prayer say something like this, using landmarks by where you live.
"I forgot to do the lesson. Hmm...what shall we do. Wait! I think something is coming, something special. I see in my mind someone getting off the plane (bus, or train, whatever is near by), they are coming down the freeway. Wait.. I think someone is coming by the grocery store, they are coming down the street. They are bringing the COOLEST thing ever. They are driving up. They are coming up the path. (Run to the door and listen with your ear to it). I think they left the Coolest thing ever on the porch!! I think they left. Who wants to open the door and see what it is?" (Be dramatic, use things around your house, make it exciting)
Once the package is brought it in, open it. Tell how wonderful the gift is. Tell them how you received your testimony of the Book of Mormon. Read your favorite scripture out of it and tell why. Bear your testimony.