I don't have a geeky tattoo, but I have a geeky story associated with the one that I have. After a weekend of heavy drinking, three of us decided to get tattoos. I picked out a Celtic themed Griphon, very tastefully inked onto my right calf. As we were all fairly young and very broke (after a weekend of heavy drinking) all I could afford was the line drawing, no color/shading.
So I start minding my P's and Q's and in a couple of months I have enough to have someone color in between the lines. What do I do? I have them print the design stencil, which I immediately take to the office to duplicate. I come home with a ream of stencils and I sit down with three of my younger sisters and we start coloring them all in. Crayons, Markers, Colored Pencils... You name it, we colored with it. At the end I took the three that I liked the most back to the Tattoo shop and said "Which one of these won't look like crap on my skin?"
The end result has held up well all these years, and that's my geeky tattoo story.