Known for being Japan's capital of comedy, Osaka is an outgoing, lively, party city.
Many of Japan's popular comedians are from Osaka, and the local dialect of Japanese - Osaka-ben - is often mimicked and used around the country in casual conversations. Older women here are famous for fashion such as animal-print jackets, and it's said that if you pretend to shoot someone with your fingers in the city, they'll act out their death and take part in the fun. I haven't tried that personally, but I've seen the leopard prints!
Locals like to drink here, many times until the wee hours of the morning, and are generally more likely to be open to random strangers than other cities. While there's room for both, people often tend to be either Team Tokyo or Team Osaka. Culturally, the two can be rather different, even to things like which side of the escalator to stand on (Tokyo: Stand on left. Osaka: Stand on right.). I tend to be more Team Tokyo, but I have friends who prefer Osaka.
Umeda, Shinsaibashi, Dotonbori, America-mura (America Town) and Namba Parks are some places to venture to and check out.
Umeda is right next to Osaka station and vibrant at night. There are small streets full of izakayas, perfect for jumping in for some casual Japanese food and drinks. Shinsaibashi and Dotonbori have a lot of shopping, and are some of the more photographed areas of Osaka. Both are electric at night, and the Glico Man sign in Dotonbori is one of the iconic sights in the city. America-mura is another shopping area and has streets of boutiques geared towards the younger crowd. Namba Parks is a shopping mall that serves a double purpose as a park. It's fresh architecture attracts everyone from casual shoppers to couples to photographers.
Some of Osaka's famous foods are takoyaki (doughy balls with a piece of octopus inside), okonomiyaki (a type of Japanese pancake), taiyaki (a fish-shaped, doughnut type of snack with a variety of fillings inside) and udon.