The carousing rules are based on the original rules by Jeff Rients, and Jeremy Deram came up with the simple way to make them jive with the DCC RAW experience system. One notable change is that I’ve made the consequences into a d100 chart. The original carousing rules has the PC make a save vs. poison, and if they failed the save they rolled a d20 for consequences. To determine the percent chance that there would be no negative consequence, I averaged the save vs. poison number for a 1st through 10th level fighter in Labyrinth Lord rules. As far as making some negative consequences more likely than others, that was purely personal choice.
All of the examples on the thief reference sheet are drawn from DCC RPG, save for the DC 10 pick pocket example, which I added myself.