It means to act upon something, or get some "nuts" In other words, get some cojones or shut up

i didnt see the movie, but suspect that it means: be more brave/bold (nut up. get some nuts/balls/guts) or stop complaining/whining (shut up)

Are you sure you heard it correctly? There is an expression; "Put up or shut up" which means that the character needs to o have to endure (something unpleasant) without complaining or take the action necessary to remove the source of the unpleasantry

It means be brave or stay out of it.

ja~ my mouse isn't working very well