Step 1: Insult the hell out of them... they've just claimed that any form of prescriptivism is a form of cardinal sin; Step 2: screw syntax. if they can figure it out in less than 10 minutes, you're not trying hard enough; Step 3: psychoanalyze every minute choice of every word.
etymonline.com allows you to be truly rediculous here; Step 4: await your forum ban >_>