Named after the strategy used by the German's in World War 2, where the army would rush passed a certain point or line with everything they have. Blitzkrieging is when someone steps over the line appropriateness really quickly, usually with just one comment.
Guy 1: "Hey man, sorry I'm late. I just got back from your mother's house."
Guy 2: "Yeah well I fucked your dead grandmother."
Guy 1: "Wow dude, too far. Stop Blitzkrieging."