Whenever one of my family members want to borrow my laptop to check their face book or email or anything, I throw them onto IE since Firefox has all the crap I look at: groups of youtube vids I repeat over and over cause I like the music, Fanfiction... I don't want them looking at that, stuff I google up, more fanfiction, this place, and of course, my 4chan tab...more or less just /m/.
But they wouldn't find anything in my history since whenever I do look for certain things, I private it. Although, if they did check the /m/ tab, they would somehow wander into /b/...and then maybe some of the worst parts of it.
...anyone ever accidentally wander over to any other part of 4chan just cause you were curious?