There's nothing very exciting to tell ...
My Tumblr name is the same as my Livejournal name, Dizzojay.
Dizzo is a nickname based on my surname that I've had for years, long before I joined fandom and I'm just Dizzo on Fanfiction.net which was my first fandom online home.
When I decided to join Livejournal, there was already a Dizzo on there, so I added my first initial, J, or Jay.
Ever since then, I've been Dizzojay on most of the online platforms I've joined, including Tumblr, which I no longer use or hardly ever visit because there's just too many crazies over there for my liking!