put up or shut up

put up or shut up  {v. phr.}  {informal}

1. To bet your money on what you say or stop saying it. — Often used as a command; often considered rude.

The man from out of town kept saying their team would beat ours and finally John told him "Put up or shut up."

2. To prove something or stop saying it. — Often used as a command; often considered rude.