Osaka-ben, in brief
Osaka-ben is the local dialect of the wider Kansai-ben family, known within Japan for being blunter, faster and more expressive than standard Tokyo Japanese, with its own vocabulary, verb endings and intonation. It's associated with directness and warmth in roughly equal measure, and locals are often visibly proud of it rather than treating it as a regional deviation from a 'correct' standard.
Manzai and Osaka's comedy industry
Manzai — a fast, two-person comic dialogue format built around a 'straight man' and a 'funny man' — is closely associated with Osaka, and the city is home to Yoshimoto Kogyo, Japan's largest talent agency for comedians. Namba Grand Kagetsu, right in the entertainment district, is one of the main theatres where manzai and rakugo (comic storytelling) are performed live.
Why it shapes how the city feels
Even as a visitor without the language, this comedic, direct local character is noticeable — in market vendors' banter, in the tone of shop signage, in how readily strangers will strike up a conversation. It's a large part of why Osaka is often described as Japan's friendliest big city.