Could it possibly be a reference to the Christian biblical passage of Matthew 7:6? "... and cast not your pearls before swine lest they be trampled."? It modern, non-religious use, this means don't waste your time or energies on people who won't appreciate them such as "swine" (pigs) trampling on the valuable "pearls" that you throw to them because they do not know their worth.

Susu, do you have a bit more context around the statement to "drop your pearls"? It could mean different things. Maybe it was about pearls of wisdom (whether stated sarcastically or not), or ... I don't know. It depends on context. It's not a common phrase that stands on its own to my knowledge.

This is a difficult one to explain - it has a lot of references within references within references. In movies and tv shows in the 40s and 50s, middle class and upper class women would often wear pearl necklaces. In those movies and shows, when they were distressed or upset or sad or shocked, the actresses would grab their necklaces in a fist. It was used so often in movies, that it is considered overacting - and silly. When you say that someone is "clutching their pearls" it means they're acting more distraught than they really are (usually to prove to other people how upset they are). So, when one character says "drop your pearls," he's telling the other character to "stop clutching your pearls." Or in more words, he's saying "I know you're not as _____ as you're pretending to be, so stop pretending to be ____." It is closer to "stop pretending to be so surprised."

With the context that Sarah used to drink a lot, now has a baby and says she doesn't drink anymore, her friends got really surprised. So Sarah says "don't drop your pearls". I think Sarah is being sarcastic as someone mentioned earlier. Sarah might be insinuating that the listeners think they are better than her and are perhaps being falsely dramatic about the fact that Sarah has stopped drinking, when perhaps they have their own problems and should not act flabbergasted about someone else's issues, and should not think they are better than her. But that's just my guess based on the bit of context I have.

It is also a great drama to practice listening and see how people speak English in their daily life.:D