Sometimes American English doesn't seem to make sense. Like this:
A: Gloria has a lot of things going on in her life right now.
B: Yes, she does. Her parents are sick. Her car is not working. She's building a new house and she just got a new job.
A: Wow! That's a lot of stress. One more thing and she's going to be a basket case!
Will Gloria really become a container for baskets? I don't think so.
If you experience a lot of stress or try to handle too many things at the same time, your life might become very difficult. The nervous strain or tension might wear you out and leave you with a sense of hopelessness. That's what a basket case means.
And that's English in a Minute.