Roistering is to quaffing what Defcon Three is to Defcon Two.
It is a deliberate escalation of an evening spent in a pub into reckless practical joking, hinting at the existence and then the resolution of old grievances, and dirty looks exchanged, until a tiny little spark can set off a good old roister. Roistering is the reason why the Mended Drum has been mended so often. This sort of roistering is an exclusively male activity.
The female equivalent of roistering has been described by Fred Colon and Nobby Nobbs as minge drinking. This is an arena where the weapons employed are - mainly - cerebral rather than physical, although any drinking session involving Watchwomen such as Sally von Humpeding (vampire), Angua von Überwald (werewolf), and Cheery Littlebottom (dwarf) is likely to have its moments of interest. Add in other identified policewomen such as the redoubtable Precious Jolson and a honorary copper such as Tawneee (well, the Watch girls accept she has to don a police uniform occasionally in her own trade and are inclined to be generous about this), and interesting events of a hopefully sub-lethal sort will no doubt follow.