Introduction:
Another great way to use the Joker Tube / Stratosphere magic trick is for the following gospel presentation:
"The children's worker discusses life's priorities, and how it should be that you think of YOURSELF last (the letter Y), then OTHERS (letter O) and JESUS (letter J) first and foremost, as our top priority (red to represent the blood of Christ) This of course spells JOY. We may start with good intentions, but what often happens is we lose our way, we make mistakes and get sidetracked. As you explain this, you re-cap the letters and put the balls in the tube - green, yellow, then red. But when you take off the cover...everything is topsy turvy! We've forgotten the top priority in life, and pushed Jesus to the bottom. But when we are at rock bottom, it's Jesus who can lift us up again.
Remove the red ball, then explain that there are Christians who go to church (show wooden box, drop red ball inside) but who are really leading empty lives (open the box to show it has vanished) Going to church is important, but to really connect with God, we need to remember our priorities... putting Yourself last, then Others, then Jesus (reveal tube again, showing the red ball has returned on top of the other two, all in the correct order! To really experience the JOY of God's love, we need to put Jesus first."
When you read this for the first time, it may sounds very complicated. But to be honest it is a very easy trick and presentation which enables you to explain the gospel in a school assembly, during a preach, as a children's moment in a church, etc. 
In the video below the British guys from Mission Magic demonstrate how you can use the Joke Tube to do this JOY(full) gospel presentation of the gospel yourself!
Themes:
Life's priorities, gospel presentation, JOY, Christ first