m'jig - something you can't name because you're too dumb to remember

something you can't name because you're too dumb to remember it

I don't know what that thing is. It's just a m'jig to me.

That gadget is a m'jig. I don't even know what it does.

He tried to explain it to me. I just said, 'It's a m'jig. I don't care.'