From 2008-09, I was Oliver Hagamy, which was the name I gave to one of my favorite Lego minifigures at the time (I still have him somewhere).
In June 2011, I got a PlayStation 3 for my birthday. My dad started creating an account for me and asked what I wanted my username to be. I hadn't really formulated an idea, so I just rattled off some cool sounding letters/numbers related to cars. That name was XR-7 (after the Mercury Cougar XR-7, even though I don't really care much for that particular car). Top contender against XR-7 was XLR (Cadillac XLR).
When I started playing Blockland again in 2012, the name followed me.