This spray makes anything almost indestructible

Line-X, the spray on material primarily used for the beds of flatbed trucks, may have found its true calling:

Internet videos of people making things indestructible.

From eggs, to bricks, to car bumpers, to just about anything you want to turn invincible, Line-X can be sprayed on.  Then you can invite your friends to try to smash it with a sledgehammer (*Disclaimer: do not actually invite your friends to smash it with a sledgehammer unless you have proper safety gear and supervision available.  That kickback can be a bitch).

Also, the stuff isn't technically "indestructible."  Keep that in mind if you plan on taking your experiments to the extremes.

Check out a mass of people attempting to destroy Line-X'd items