Usage and meaning of "占我的便宜" My understanding of 占我的便宜 means something similar to 吃豆腐 and I have never heard it used outside of taking sexual advantage. Can this be used in other contexts? Google translate suggests it means "take advantage of me", in English this phrase could also be used to take financial advantage or using someone for your own personal gain, is this the same usage in Chinese?

Further to this question, how did this phrase come about, why were these specific characters combined to make this meaning?
"占我的便宜" and "吃豆腐" are all disadvantages for usage with nagetive meaning for daily Chinese people.

However, the first set phrase is NOT ONLY used to women but to other things as well. We usually use this phrase to describe a senario that someones (tries to) gain sth at the expense of others, but the expense is very little for the others. And the fixed one is very similar to "揩油"(ShangHai dialect).——This is very similar to you.

Another meaning is that “贪小”（greedy for small gains or profits）

Now let's see some Chinese samples:

不要捡地上随便掉落的元宝、金银器物，不要占便宜，否则你极可能被犯罪分子要挟勒索！

"吃豆腐" is used when a man wanna do something ugh to a woman (especially something that is dirty)：(e.g), A man in the bus is rubbing the woman with the reason that the bus is fully crowded with people.

For more, you can see this sample.