SpongeBob SquarePants characters from least to most capable of becoming a Tumblr Sexyman
This is a joke please don't hurt me
Unfortunately Tumblr's type tends to be more on the waify side so Patrick's chances of reaching sexyman notoriety are pretty slim on top of not really embodying the snarky/cocky man type that was typically sought after. If he was a bit nicer I'd say he has a chance filling in whatever niche Sans Undertale was filling at the time.
Now I can't say that SpongeBob can't be sexy because Ethan Slater's Broadway performance has thoroughly proved me wrong in that regard, but the cartoon sponge as we typically know him feels a bit too goofy and innocent to have any sex appeal. It'd be like making Mickey Mouse or Mario a sexyman. Also he's literally a square.
"But Bill Cipher is a triangle!" I hear you say, "and they still sexualized him!"
And to that I say Bill had the benefit of being a villain. Not only that but in a show that not only had child protagonists, the few adult characters that did exist weren't exactly sexyman material. Bill was a case of limitation breeding innovation (see also: Onceler). If Bill was a well meaning magical triangle man surrounded by handsome twinks I don't think there would have been nearly as many Tumblr users lusting after him. SpongeBob has a better chance of reaching "Cinnamon Roll" status than "Sexyman" status.
Eugene H. Krabs
Now hear me out because while I'm not sure Eugene would be capable of reaching the 2012 Tumblr version of a "Sexyman" I think he's still got a few things going for him. He's older, he's a father, and his navy buddies literally nicknamed him "Armor Abs Krabs". I think he can find his way into Twitter Sexyman status as they typically appreciate the more seasoned dilfy types. Also he's sugar daddy material.
Larry the Lobster
Larry is the one of the more traditionally attractive characters in the show in that in-universe he is meant to be seen as such. He's got a lot going for him: he's handsome, selfless (he is a lifeguard), well meaning, and a little dumb. That being said, those traits feel more in tune with today's standards that favor meathead himbos with with hearts of gold (see also: Clone high JFK) rather than the 2012 cynical lanky men with cocky attitudes. Speaking of which...
Squidward Q. Tentacles
He's skinny, he's a smart ass, he's cocky, and he occasionally plays an antagonist role. With SpongeBob being too busy taking up the "Cinnamon Roll" title, that leaves his costar ripe for the picking, especially when those few shining moments of Squidward actually caring for said cinnamon roll shine through? Prepare to scroll by gifset after gifset of the latest Squidbob moments every week.
He'd practically have Tumblr eating out of his tentacles.
He's got most of what I mentioned above about Squidward on top of the fact that he's a villain. He has a rivalry with another strong sexyman candidate so you KNOW folks who shipped Catradora or Solider 76/Reaper would be all over this enemies/lovers shit. Couple this with how little screentime he has which allows users to project any number of preferences (read: kinks) on his less than fleshed out personality and it makes him prime for the kind of sexyman who gets dozens of rp ask blogs based on him that flesh him out more than the entire series could ever care to do. "Any Squidward ask blogs wanna rp?"
Sheldon J. Plankton
If you asked me 1 year ago whether Plankton was capable of being a tumblr sexyman I'd laugh. Sure, his Broadway version had quite a few folks hot and bothered, but just like with SpongeBob, I don't think the character himself has a leg to stand on outside of that. I know that Plankton tends to show up in jokes about the types of characters that would be considered sexymen if their shows premiered during this era of tumblr since his cynical villainous nature works in his favor, but in the end I'd say his over all silly nature works too much against him.
That is, until Deltarune chapter 2 came out and y'all fell in love with that weird short puppet robot guy. I don't understand it honestly but I've also never played Undertale or Deltarune so I won't judge. I've heard some say that the Spamton sexyman phenomena exists more on TikTok than Tumblr (which prefers to give him the "my little meow meow" title) but as far as I'm concerned it walks and quacks like a duck. Sheldon is absolutely sexyman material.
I can already here you all doubting me but just follow me for a sec. He's got so much of what I've mentioned above that he is practically begging to become a Tumblr Sexyman. 1) He's a minor villain with an appealing enough design to catch our attention. 2) but he has a flat enough personality [due to few appearances] to project onto. 3) He was clearly shown to have a soft side on multiple occasions. 4) He's surrounded by characters who are, to most, not sexually appealing. 5) He's hot. (BONUS: he already comes w a tickling fetish if you're into that kind of stuff.). Manray has the sexyman recipe patented and we've all been fools for not noticing it sooner.