I am liberally stealing (and editing) Jeff Rients' carousing rules found at: http://jrients.blogspot.com/2008/12/party-like-its-999.html
At the players' option, they may attempt to earn extra XP by carousing around the City-State. Carousing consists of the PC spending a significant amount of gold on ale, gambling, prostitutes, or other forms of nighttime debauchery. The process works as follows:
1. The PC chooses a neighborhood that they would like to carouse in.
2. Depending on the neighborhood, the PC can spend the following amount of gold to gain the equivalent amount of xp:
- Red Bazaar: 1d8x150
- Sanctum: 1d10x200
- Temple District: 1d6x100
- Wyrd Quarter: (1d3+1d5+1d7)x100
As more neighborhoods are discovered, the list will be added to. Characters who are members of the Thieves' Guild members can spend an extra 50 gp to the multiplier to gain that much bonus xp. Their friends can do the same, but only 25.
3. If the PC does not have the amount of money that they roll, they only gain half the xp as the amount of money they have, and all money is spent.
4. The character must then make a saving throw versus poison. Upon failure, the DM will roll on the 'Carousing Mishaps' table, which will be different for every neighborhood. Any night in the Wyrd Quarter will automatically cause a roll on its table.
Please note that many of the events on the mishap tables will put characters in either difficult, costly, or funny situations. Many could also lead to future adventure hooks and affect relationships with various factions in the city. Regardless, utilizing these rules is definitely a risk, but potentially worthwhile to level up more quickly and prompt more (mis)adventures.
Fortune favors the bold, indeed.