1. The act of erasing all evidence of wrong-doing. A metaphor
based on the common custom of clearing one's browser history on a computer
after watching porn
2. or more literally, erasing the viewable browser history of a computer to hide the fact that you just watched porn.
Dominic: "Dude, I didn't do the Algebra II homework last night, so I did it all over lunch"
Ben: "When it comes to clearing your browser history, you work faster than anyone I know."