Hit up for
Definition 1 of 1
Pro Tip 1/3Informal Usage
The phrase is casual and might be considered too relaxed in formal or professional settings. 
I wouldn't hit up my boss for a loan; it's too informal.
Pro Tip 2/3Direct Approach
Using this phrase implies directly asking for what you want without beating around the bush. 
Just hit me up for the notes if you missed the lecture.
Pro Tip 3/3Casual Relationships
It is commonly used among friends or peers rather than with strangers or superiors. 
I hit up my classmate for some advice on the assignment.