The night before our encounter with the CN terror, the three of us gathered to do our final preparations. Basically it was PY doing the solving; ZX and I merely slacked around, flipped through our notes and eat cookies.

I was looking at the fomulas for the best fit line, and asked them whether the most likely to be useless equations had to be committed to memory. Parameter 'a' had the formula

SSxy
SSxx

The perverted me immediately recognised it as 'sexy'/'sex'. We had quite a laugh about it, then I realised that it 'SSxy' was more dominant as it was on top. It was ZX , however, who added the final touch to the joke.

He said, "It's only natural that those with XY chromosomes end up being on top."

Hence, a=SSxy/SSxx is now known as the man-on-top formula.

Smart eh? ;)