Ah OK well our home computer has a virus and is getting fixed tomorrow by some guy who's coming to our house. I'm 16 and have been using this comp to stream porn for some years now and tried to delete cookies and temp Internet files n stuff but I'm worried that he'll find the porn in some way and my mum finding out what do you think?

If my mum confronts me about it what do I say to her?

Tell her you are a normal 16 yr old with normal curiosity and promise not to do it anymore.

Explain it to her by using this song

YouTube - trucks - it's just porn mum

That way no awkward conversations :D

Old enough to watch it, old enough to admit it and face the music to it.
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PS many porn downloads will be where the virus's come from

Any thing done on the web comes with no reasonable assumption of privacy. In short you could be found out and chances are you will be found out.