ATDTDA (2): "out on the town" (33.2)

[Tim Strzechowski]

[...] who were "out on the town," owing to a fortunate wager Merle had made earlier that day" (p. 33).



out on the town:  Phrs. An evening indulging in the nightlife of a town or city. {Informal}
 
http://www.peevish.co.uk/slang/o.htm


When you go out partying and having fun at public places like bars, restaurants, and theatres, you are "out on the town." Example: "I arrive Friday evening and I'll be done with all of my work." Answer: "Great; we're going out on the town!" When you are "out on the town," you are out at places where people enjoy themselves and celebrate together. Example: "Do you want to join us tonight? We're going out on the town." Another example: "Are you staying home tonight?" Answer: "No way! I'm going out on the town!" 

http://www.goenglish.com/OutOnTheTown.asp