California Love

All Eyez on Me 2Pac
Bring proper protection from sexually transmitted diseases when you travel to Los Angeles
Dr. Dre is referring to Vidal Sassoon jeans worn by women in the 1980s. Just before this he mentions he'd been doing rap for 10 years, so it is a reference to the 1980s.
2Pac wants to hear the music from Dr. Dre, a member of influential rap group N.W.A., who became more known for his producing talents: creating beats (or, the music tracks rappers rap over) for Snoop Doggy Dog and in this case 2Pac.
2Pac has so much diamond jewelry that it looks like he robbed Librace, a really flamboyant and fancily dressed piano player who always wore flashy outfits and lots of jewelry
you should always keep a condom with you when you go out in the greater Los Angeles area because a lot of people have sex and you could catch a sexually transmitted disease if you don't wear one