I’ve painstakingly found all (most) of the words that you cannot search for on Pornhub. If you try, you will get redirected to the warning in picrel. Disclaimer for the jannies, I do not endorse any of the below described words, this is for informational purposes only.

Kid Child Toddler Infant Kindergarten Underage XX years old (with any number less than 18) Pedo Pedophilia Jailbait Elementary Middle school Youngest (not just ‘Young’ on its own strangely, although ‘young’ causes a special “No results” page, which is not the typical no results landing page) Loli (but not ‘Shota’, although ‘Shota’ causes a special “No results” page, which is not the typical no results landing page) Daycare Little Boy Little Girl Young Boy Young Girl Omegle (‘Incest’ is allowed, but causes a special “No results” page, which is not the typical no results landing page) (‘Zoophilia’ is allowed, but causes a special “No results” page, which is not the typical no results landing page) (‘Epstein’ is allowed, but causes a special “No results” page, which is not the typical no results landing page) (‘Rape’ is allowed, but causes a special “No results” page, which is not the typical no results landing page) (‘Abuse’ is allowed, but causes a special “No results” page, which is not the typical no results landing page) There is at least one other word that is fully banned but for legal reasons I won’t post it here.

EDIT: the last word is Boystown