Things People Say When They Mean the Opposite Part II

I forgot about this one:

"A light bulb went off in my head" = "A light bulb went ON in my head"
What you mean is that a sudden bright idea occurred to you, illuminating your thought processes in some way. When a light bulb "goes off" greater darkness is naturally the result. The only bulb that illuminates when it goes off is a flash bulb (people under 30 may need to google "flash bulb") and therefore the phrase "a flash bulb went off in my head" works fine. That's the original figure of speech I think.

and one more in common usage:

"this new idea is based off something" = "this new idea is based ON something"
What we mean is that our new thought begins with and is built upon an existing foundation. A base is a thing on which multiple structures might all be anchored, including our new one. A new idea might "spin off" an older one or "take off" from it, but to say that our innovation is "based off" something implies the opposite sense while making no sense.

"Don't some of these verbally priggish bloggers have something better to do?"

Yes, and we'll get back to it now.