What does the idiom thrown up to them mean?

The idiom "thrown up to them" is not a common idiom in English. It's possible you've heard it used in a specific context, but it's not a standard phrase with a widely understood meaning.

If you can provide more context, such as the sentence where you heard it, I might be able to help you understand its meaning.

For example, if someone said "I threw up to them what I thought about the project," it could mean they expressed their opinion forcefully or even angrily.

However, without more information, it's impossible to be sure.