This story is rather annoying to explain after a million times, but whatever.
I'm friends with a kid who is known for his long, red hair. At one point, someone with an affinity for giving out Disney nicknames gave him the name "Ariel", the name of the "The Little Mermaid."
I never had a nickname, until I met the person who gives out the Disney names. Because I only hung out with her when I was with "Ariel", I got the name "Flounder," essentialy the "sidekick" of the Little Mermaid.
The underscore I have here is because I had numerous problems registering, and I never rcieved the e-mail for "Flounder." I stuck an underscore on it, got it sent to my hotmail, and it worked.
On GameFAQs, the "3345" comes from when I played RuneScape. My name of choice was already registered, and the first suggestion on the list had the "3345" on the end. It stuck. If there's already a "Flounder" registered when I'm trying to join a site or whatever, I add the 3345.