My nick does not refer to any undercarriage protection, or cosmetic enhancements on my VX, as you may have suspected.

I've actually used this handle online since the early 90's, (long before I had the need for any such vehicle augmentation). As yal^ pointed out, anonymity is always a concern on IRC. So when I started hanging out there a lot I decided I needed a good handle, about the same time I heard the Jerky Boys refer to somebody as SkidPlate, and it stuck.