Calling someone a 'basket case' is an insult and implies that the person you are talking about is crazy. Be careful using this expression in public. It's generally an insult about someone's mental or emotional stability, although a lot of English speakers might use it jokingly. A 'basket case' can be someone who is considered to act a bit crazy or have trouble dealing with other people in a personal or professional capacity but it can also be a situation or an organisation which is considered to be unstable or to be a risky investment. You can use this in either social or professional situations, but if you're describing someone when using it, be careful who hears you say it!

1. I'm not surprised that Eddie went ballistic like that over something so trivial. He's always been a bit of a basket case.
2. When I got the call with the good news, I was so happy that I burst into tears of joy. I'd say that the other people in the shop were looking at me like I was a complete basket case!
3. Thanks to the discovery of huge oil reserves, the country went from being an economic basket case to one of the richest nations in the world.

1. When the job cuts began, I was so worried about losing my job that I turned into a basket case! Thankfully, I survived the cull.
2. The company was once at the top of the food chain, but due to years of mismanagement and poor investments; it has become something of a financial basket case.