>>31673229Hellboy is a comic book character. He's a demon from hell that was raised to be a good guy. He smokes drinks, has fun and is a paranormal investigator who shoots ghosts and shit in the head with a really big gun. He was also in a couple movies, first was okay, second one was fucking awesome.
The joke is a play on "Demi-Boy" which is a tumblr term of demi-sexual meaning you're more attracted to romance than sex and don't care what gender your lover is, just that you are loved. Why they count this as a gender and not a sexuality, I have no idea, probably because they're gay retards, but let's not get too sidetracked... The joke is Dem-Boy sounds like Demon-Boy so they threw in a symbol for Hellboy.
I picked apart and explained the entire joke. It won't be funny now, but at least you know.