This is sound advice. OP, you never masturbated at work, you must be confused.

I guess people downvoting this answer never read 1984 and never heard about Mutability of the past.

While this answer seems backwards, I think the point is that if she actually "caught" him, she must have made a deliberate attempt to violate his privacy. If there was a crack in the blinds, she had to stop and look through them -- it's unlikely she would have seen anything just when passing by.

Masturbating is not disgusting BTW

@KorayTugay I interpreted "1984" as a dystopia, warning of what could happen if intellectual dishonesty were allowed to go unchecked. This answer is an insult to the OP, implying a lack of honesty. It is also bad advice, because it converts a forgivable incident into lying to managers, and possibly even perjury. The OP may get away with it, but if not it makes the consequences much worse.

You can lie to others, but you can't lie to yourself. The only part of this answer that makes sense is "make sure you don't even mention such a random possibility in any conversation with your colleagues".

The same spirit as my answer, but takes it one notch further. I would not lie about it, just be quiet, but ok.

This answer also assumes an extraordinary skill with lying and manipulation. Have you ever tried this level of deception before? How did it work for you? Because it is quite comical when people who are not skilled at deception try this.

Just to be clear, if she truthfully reports what she saw, you are advising OP to break the law by making a false complaint of defamation? Something which might require OP to commit perjury if it went to court?

Are you seriously suggesting gaslighting and perjury?

I'm not sure how relevant this advice is. There are no allegations. Why lie when you are only lying to yourselves?

@Barmar that isn't even remotely what this answer is implying.

@EdHeal It's fine in private, it's taboo in public. A private office at work is a grey area, but I think most would consider it highly inappropriate.

@Barmar - An office at work isn’t private. There is no gray area.

@KorayTugay Many of us read 1984 and understood that it was intended as a warning, not a how-to.