Listening to Keith re-read his dad's 86 emails, he mentioned something about transposing the numbers that I didn't pick up on the first time. So it sounds like he's not actually talking about an 86 sexual position but 68.
If you search for the '68 position' you do get a lot of articles with headlines like he was talking about.
Not that this is any less crazy. If someone has 96 in their email address, I doubt many of us would make a connection to 69 but there you go.