Vanillafag is an insult/mockery used against someone who primarily masturbates to conventional sex without any fetishes, also called vanilla sex. It is mainly used in the hentai community. Vanillafags are mostly found in comment sections of content that features morally questionable fetishes, like scat or netorare.

No Bull Shit, and old hacker acronym which is usually used to signify that the talk will be serious.