A great-grandmother in Rockford, Ill., received a surprising appraisal from Antiques Roadshow and has decided to auction off her treasure: A antagonistic letter from crooner Frank Sinatra to rabble-rousing Chicago columnist Mike Royko, according to the Chicago Tribune. In the letter, Sinatra said the columnist was a “pimp,” and suggested the two have a hair-pulling duel (Sinatra was upset at a Royko column that accused Ol’ Blue Eyes of wearing a hairpiece). Vie Carlson purchased the letter back in 1976 for $400. At a Roadshow taping on July 11, appraiser Simeon Lipman told Carlson she might be able to get $15,000 or more for the letter, so she’s selling it next spring through Freeman’s Auctioneers in Philadelphia. The episode will air this coming February.