Timmy comes from the three archetypes of players from the lead designer of MTG:
Timmy is the guy who wants to play big creatures on curve and get big splashy but simple effects, hence the unga bunga.
Johnny is the guy who wants to experiment and brew crazy meme decks and combos, even if they don't win if they did "the thing" they won.
Spike are the hyper competitive players who just want to win with the best deck in the meta and play it perfectly.
This the article he wrote about it, it's very interesting, you start to see how many cards in MTG and LoR are usually targeting one of the 3 archetypes of players
https://magic.wizards.com/en/news/making-magic/timmy-johnny-and-spike-2013-12-03