Yep, walked in on my brother changing over a single GPO to a dual plug GPO in his room way back when. Coversation went like this:
Me: WTF are you doing?!?!
Him: it was cracked and I want the extra plug
Me: you are not a qualified electrician
Him: It's okay, I've switched it off....(shows me the outlet switch in the off position)
Me: did you at least pull the Fuse or switch off the main switch?
Him: ????? Urrrrrr???
Me: ............ I'm just going to the fuse box, I'll come back in a minute to slap the stupid off you.