Unfortunately, Charles Mulligan’s Steakhouse closed in Parks & Rec, and ever existed in real life. So you can’t get the poster, right?
Wrong! There have been multiple people to sell the poster online (check ebay) and you can get the original poster that it’s based off. The boxer in the picture is one Mike Conley, popularized across the internet as overly manly man.
An actual Charles Mulligan’s Steakhouse print
Get an original Mike Conley poster here
Ron Swanson's Office 