I was literally watching this video an hour ago. This guy is nuts but he does make sure to mention safety in every video. Because of him I will never be unsafe with lasers because I don't want to go blind forever.

My favorite laser safety poster, seen in a high-power laser lab:

"WARNING: Do not stare into laser with remaining eye."

There was, of course, a full set official warning posters as well. But that's the one I remember.

And then you have zilipoper

That video was incredibly inspiring. Time to dig out the spare chicken wire.