I am from San Diego (well, Alpine, to be precise). As they said before, San Diego is a very big place.
If you like good bars, I'd go down to the Gaslamp (Quarter). Lots of cool places down there. George at the Cove is supposedly a good place (too pricey for me).... but if you like seafood and aren't too highbrow, any of the Anthony's Fish Grotto places are pretty good. For nightlife, I'd go for Gaslamp or PB (Pacific Beach) areas for fun and hot chic... er, fine young ladies.
For more respectable entertainment, try the SD Zoo (best in the world!), Wild Animal Park, or Balboa Park (lots of cool museums, learn a lot, and a very chill place to have a picnic/lunch).
If you're a real savage, head east about 20-30 miles to Alpine/Descanso/Guatay, find a bar, and pick a fight. I'm sure NDD would like to hear the AAR.
Any other specific questions, feel free to PM.