Bone up on
Study hard for a goal or reason
Buff up on
Improve your knowledge quickly
Catch up on
Do something that should have been done earlier
Check up on
Visit a place to check something
Creep up on
Approach without someone realising
Gang up on
Harass, bully
Give up on
Lose faith in or stop believing in something or someone
Grow up on
Do or have something when you are a child
Hang up on
End a phone call with someone
Hit up on
Inject drugs
Load up on
Consume a lot of something for a particular purpose
Mug up on
Study something quickly, revise
Pick up on
Correct someone when they say something wrong
Read up on
Research
Rub up on
Revise
Run up on
Approach someone without their knowing
Sneak up on
Approach someone furtively
Steal up on
Approach a place or someone quietly or secretly