This company can trace its roots to an invention of Alex and J.F. McCullough which they convinced Sherb Noble to sell in his Joliet, Illinois ice cream shop. Noble opened this company's first store in Joliet in 1940. This company's most popular product may be briefly flipped upside-down before being served. Since 1998, Warren Buffett's Berkshire Hathaway has owned this company, and he owns a custom ukelele with this company's logo. Identify this company which for roughly 30 years used Dennis the Menace as a quasi-mascot.
Dairy Queen