A tab that can be safely retreated to upon threat of interruption by friends/family while viewing pornography. Could take the form of a Facebook page, youtube video or other sites of unsuspicious origin or motive for viewing.
You: Dude, I was getting busy on my computer, when I heard my roommate about to walk in.
Friend: What happened?
You: Well luckily I had my safe tab up, so it was a quick mouse click and I was in the clear!