Ron and Jake stand close together in gym trunks, Ron's hand on Jake's thigh.
For some reason, I was unable to find any Danny-Jake pairings. Danny and Jake are both serious, morose characters, so maybe they aren't compatible. They need Ron Stoppable's goofiness and good humor.
You might expect a lot of trios, but there aren't many, and they never portray the act itself. Here Ron and Jake are aggressively cruising Danny Phantom, who is rather perplexed at the attention.
A Japanese-infused Ron and Danny wonder if classmate Jake Long wears boxers or briefs. They are highly stylized, but Ron is wearing a "Save the molerats" t-shirt, referencing his pet mole rat, and Danny's t-shirt has a ghost on it.
(All pictures borrowed from the original artists on deviantart.com)
See also: Gay Fan Art #4: Cartoon Kids Grow Up