I guess the title says most of it but I actually had a really pleasant experience when I politely mentioned to the barman that the class 3B Kam Laserscan 1000 3D installed at eye level by the DJ was probably unsafe and could damage peoples' eyes.

I say installed but it was in fact sat on a chair on a raised stage adjacent to some steps and eye accessible within about 1ft of the aperture.

They took a little while to turn it off - in fact I warned the barman before I ordered my drinks, he served me, then I took drinks back to friends (minding my eyes) and it was still on 10 minutes later - but off in 15 minutes.

They didn't question me at all, which surprised me but they did get it switched off.

Good on you local drinking establishment