In my frat and its sister frats the universal comeback for any insult is "Hängt!"
Which roughly translates "It's on" and results in the both of you racing one on one in beer drinking. The amount of beer each drinks can vary from one glass, up to well, up to anything. but more than a gallon is uncommon.
A truely fucked up insult, or some kind of true fuckover is solved by giving the guy in question your business card, with a small tear in it. He may then choose a date, place, time, set of rules and weapon for the duel, which is to take place within 30 days. He is to contact you about this planning within 24 hours. 99.5% of the time the weapon is the Schläge, a long thin light one armed sword with a metal cap protecting the hand. Otherwise it can be the Degen (sabre) or the Glocke (handle with a sort of long metal sharp rod that handles almost like a whip)
Most members are only trained for the schlage and will turn down degen or glocke challenges