Before the hit show “Shark Tank” catapulted budding entrepreneurs with promising ideas into stratospheric fame and fortune, good old-fashioned ingenuity — and a lot of luck — could turn a mere idea into millions.

And sometimes even billions.

A look back in time, in fact, at some of the wackiest and most unexpected moneymakers from the past up until the present day will have most of us kicking ourselves and muttering, “Why didn’t I think of that?”

In these cases, someone did — to the amusement and entertainment of scores of people (and to the benefit of some lucky folks’ bank accounts).

For a bunch of fun, check out the gallery below!

And if you’ve got a favorite, share that with us by writing to [email protected].