Who is he and why are they saying his name?
Another question about sayings. When someone is speaking about a subject or two, sometimes people say “and not to mention, _______” and then they mention it anyway.
Why do they do that?
I would guess they’re referring to the biblical Peter.
And the “not to mention” thing is just a figure of speech. It’s referring to the fact that the thing not mentioned wasn’t mentioned before they said it.
It may be a corruption of “for pity’s sake.”
Oh yeah,
cite.
http://boards.straightdope.com/sdmb/showthread.php?t=355348&highlight=pete's+sake
A previous thread which may give some enlightenment.
DOH ! I should’ve used the search. 
Thanks !
My dad?
That’s what I was thinkin…
He’s just this guy, you know?
I think you’re right. He’s like Al Gettout. 
As Strinka points out, this is a figure of speech, more specifically called Paralipsis.
Originally this was an ironic way of mentioning a bad quality of a person/thing without admitting you are mentioning it. However, “not to mention” has become such a cliche in modern English that it’s almost equivalent to “and”.