You're in the shower, thoroughly soaped including your hair and the water suddenly goes ice cold. No Mic to shout for. I was freezing cold. All sorted now but why it happened I do not know.
They reckon that cold showers are good for you, I'm not so sure, its a heck of a shock to the system when it suddenly goes cold.
We do it on a regular basis, we are on bottled gas, when the bottle is getting low we call them russian roulette showers, you never know who is going to get it. Lol. X
My combi boiler does that every now and again. I think it`s called a lock out. It rights itself but it isn`t very pleasant when it does it in the middle of a shower.