How should I diffuse this situation?

OK.soo i was bored and its late,so i was about to have a night of spanking the weasel,so i went upstairs to get some lotion,but forgot that porn was already on the computer screen downstairs,but i went up there anyway.my sister,who is very opposed to porn,was having a hard time sleeping.when i heard her walking downstairs,i ran down there but it was too late.i couldnt find her for about 5 minutes but i heard her working in the sink,which is right next to the computer,so she probably saw it.when she returned to the room,she scowled at me then walked away.any suggestions.