Well, I doubt this is THE geekiest combination of things I've ever done at once, but it probably comes close.
Monday night I was watching Big Bang Theory, laughing at Sheldon recounting why he couldn't be a Green Lantern (duh, has to get a ring from the Guardians on Oa, etc.) but he could be Batman (as if), while cutting out D&D 4th edition power cards that I printed from a template I downloaded from EN World, using the Magic Set Editor for printing out home-brewed Magic: the Gathering cards (downloaded from SourceForge.net, home of open source software). While wearing a Rasputina t-shirt. (sitting in front of a coffee table piled with comics)
So, faithful and innumerable readers: you are hereby challenged! What's your geekiest combo moment?
PS: Last night at chorale rehearsal, we got The Messiah. YIKES. That puppy is DIFF-Y-KULT. I may switch to tenor.