The theme song for me and my friends to start a night of drinking was "Party Hard" from Andrew WK. Its amazing what that man can do with like 3 chords and two words.
Good drinking songs depend on the situation. If its for a big party, you want to go with more popular ones. If its just for you and friends, you can put on some stuff that more fits your fancy. Some good ones are "40 oz to Freedom" from Sublime, "Brass Monkey" and "Fight for Your Right" by Beastie Boys, "Just One More" by Mad Caddies,"Ill Drink to That" by the Bosstones, and my favorite song to drink to of all time, "Swagger" by Flogging Molly.