The. Jungle. Book.
Like i said in the comments section of a recent image, i had to have been like 6 or 7 at the time, 4 or 5 years shy of when i began noticing breasts and became sexually aware in a more normal capacity, and there i was, gettin' a boner, something i didn't even know the word for until about another 3 years (only child, no older siblings to teach me this stuff, and my parents didn't give me the talk until they caught me leafing through dad's Sports Illustrated Swimsuit Issue collection)
Ghost Clown from Scooby Doo did much the same, though.
Although i did not really discover hypno-porn until i finally managed to figure out how to surf for porn without getting caught (didn't get my own computer until i was 18, and my parents were savvy enough to search cookies and even the temp files after i figured out cookies. Took me a while till i figured out both). Probably around 16 when i discovered NVHentai, which was my prime site up through 2012, when i migrated to e-hentai. NVH is a good beginner's site because they group things very easily by category, so you don't have to know how boorus or other archive setups work (e-hentai is still a little user-unfriendly), and so i was able to re-discover The Jungle Book r34, as well as general hypno porn. Some artists from NVH's "Hypnosis" stash led me to deviantart, which got me on DA_Entranced, which finally hooked me up with the broader community, leading here.
In the span of time between not watching The Jungle Book anymore and surfing NVHentai with impunity, Inuyasha was a nice resource, as were the "Despero" episodes of the Justice League cartoon.