I don't think it's a joke. It's presented in a funny manner, but I think the user is actually asexual. I know there's plenty of special snowflakes on Tumblr who have a new sexuality every Tuesday, but you can't assume they're all like that and just deciding that they don't want to have sex. If the person really is asexual, it's no more of a choice than homo or heterosexuality.

Ah yes, parenting and sex. I never did get 'the talk' and all the way til 15 my parents blocked my eyes on any kiss scene in movies. I guess that's what happens when they are the conservative type. Then suddenly, just as I turn legal age they tell me to always use a condom. I had no idea what they were talking about. The world of sex was something uncharted to me. That is, until I discovered porn.

Thank you, Pornhub.