Have you ever jerked off with is it normal open in the background?

Probably.

But then again, I mostly use it on my phone so... Definitely.

What! No.
http://www.reactiongifs.com/wp-content/uploads/2012/09/I-dont-get-it2.gif

You should start a masturbation blog. Kinky fantasies, casual vulgar impulses, etc. Creative perversions are always interesting.

I want to say that I had it open in another window while I was using a new window to private browse.

I sometimes masturbate not to the content of what's written on the net, but to the style in which it might be written. I've successfully gotten off before by reading something someone has written on here, and jacking it to the style.

Try the foreground.