You can't tumblr properly when your parents are in the room. Hell no.
I've been pretty lucky since I don't follow many inappropriate blogs, but there's been some moments when they've walked in at inopportune times.
As someone has so eloquently dictated, "browsing tumblr when a family member is in the room is like playing Russian Roulette with a gun loaded with gay porn." Paraphrasing of course, but the point's still there.
Nah man, I don't look at inappropriate stuff. I just follow a few blogs I'm not really comfortable with other people seeing. Like, they're gonna go "What's that?", and explaining would be really awkward.