I successfully held back the urge to make a joke here. But I realize that many young people ask questions here so I won’t. (Yet, I did chuckle to myself.)
You might consider using the famous photo of Einstein sticking out his tongue at a photographer. (He basically was fed up with the “paparazzi” and it was a very human reaction.)
If your audience has basic math skills, I think it is very interesting to illustrate with some numbers just how HEAVY an object becomes as it nears the speed of light. It is an asymptotic line and I think some of Einstein’s equations are some of the most interesting illustrations of this mathematical phenomena.