What inspired YOUR username?

Wrong! But I think yours was inspired by WWE. (Dedede is a royal person, and his final smash shows him in a wrestling ring. This is a clear reference to the "Royal Rumble" pay-per-view event.)
How did you guess!?
Mine is my Mario Bros. OC, Nellie Rose Morningstar. She's my official online persona and I ship her with Waluigi...
you have three guesses, and two of them are free.
Mine was taken from a comment I made during a live stream I did of a Pokemon HeartGold playthrough. It was a name suggestion for my player character
I had this screen name back in the mid-1990s, before anybody knew what the internet is. I was trying to type "Ihsan's Shade," a card from Magic: The Gathering, but it was taken so I had to add three numbers.
It's my Initials combined with my Birthday.
I just wanted to make mine a little simple, yet made me feel like a master. Also my profile pic is a Mario picture (kinda). It's Singapore Speedway from Mario Kart Tour. But, since I've been into Mario Kart for about a year, I just wanted my username to let the world know, Mario Kart is in me.
My username on the Mario Wiki itself is Sparks because I've helped a lot with Mario + Rabbids Sparks of Hope articles + I love the game. My username here is SparksMarioWiki because "Sparks" was already taken.
I took mine from NEO: The World Ends With You, one of my favorite games currently. "Swallow" is Rindo Kanade's (the main protagonist of the game) online friend who he often texts and plays FanGo with, though he does not know who they really are.
Back in February - March 2020, not long before I joined here, I made sprite edits of various Mario games and characters (e.g. if Luigi was in Super Mario Land, that sort of thing). One of the ones that I did was a Luigi-themed parallel to Goombario by recoloring his hat from blue to green. I called him "Goombuigi", following Goombario's naming scheme. When I signed up to the wiki and the Boards, while thinking of a username to use, the name Goombuigi came to mind, and since Luigi is my favorite Mario character, I figured that name suited me well.
My username comes from a somewhat obscure card game called Killer Bunnies and the Quest for the Magic Carrot. One of the cards is called Bunny Budd. This card always stuck out to me because of how incomprehensibly bad it is. It is easily a bottom 10 card in the game. Without explaining how the game's mechanics work, in short, it basically does nothing. It's a really funny card to me, and I think the art on the card makes for a good avatar. I love that stupid grin.

The "Viable" part of my username is just some ironic humor - Bunny Budd will never be viable.
i've always been the joker of the deck, and thus i use Chuckles. the 17? i don't honestly know, but hey, atleast i can joke about being the 17th model in a model line.