Make proverbial lemonade from lemons?

"If the world hands you lemons, make lemonade". It's an old saying, and assumes that no one wants lemons. If that's true, then the expression means to make the best of a bad situation, or turn it to your advantage.

Still, I see lemons being sold in stores, so I guess some people find them desirable. Kind of disregard this paragraph as irrelevant - I've just never cared for the bright, cheerful comments when things go wrong. It has nothing to do with your question.

to treat this event like the well- known phrase, "when life hands you lemons, make lemonade" (make the best of a bad situation)

A 'lemon' is used to refer to as bad. The car he sold me was a 'lemon' means the car was bad, useless, etc.