Said when the would be, baller is talking all the shit to get what he/she wants
Another way of being called out after action has been taken.

When some boy or a man act very feminized and has behavior that is more appropriate for the female gender like gesturing or liking some things that it is not usually for guys to like ( such as makeup, fashion, etc.).When that boy or a man decided to change and to start acting and liking things that guys usually like(such as football ,beer etc) we could say that he Man up himself

to gain the perspective of an adult (usually male) in order to achieve a goal.

1.) To fulfil your needs to become a macho, toughened up, non-sissy lala type of man

2.) To "man up!" refers to "don't be a pussy", "wipe them tears", "man the freak up!"

3.) To achieve a fathers personal hope of becoming a man