Well then, the solution is to make it look less like work, so your brain isn't fooled.

Get rid of the tasteful orange-and-grey colour scheme, and go for a purple-and-black design inspired by videogame forums. Set the font to Comic Sans. Add user avatars, dancing hamsters, a "funny sound effect of the day" button, and rename the site from Hacker News to "Chat About Random Crap With Strangers From The Internet".