It's grammatically incorrect French. The correct sentence would be: "Je ne savais pas trop ce que je...".
Here's a breakdown:
* Je: I
* ne savais pas: didn't know
* trop: too much, really
* ce que: what
* je: I
The phrase is often used to express uncertainty or a lack of clarity about something. For example:
* "Je ne savais pas trop ce que je voulais faire." (I didn't really know what I wanted to do.)
* "Je ne savais pas trop ce que je ressentais." (I didn't really know what I was feeling.)
It's important to note that the phrase is informal and often used in spoken French. In a formal setting, you would use the correct grammatical structure.