Opening verse could go something like ...

PERVING ON MY MIND

It's knowing that your door is always open
And your legs are spread a lot
That tends to make my cock grow hard,
With precum near the top.
And it's knowing I'm real excited
By sex and pent up loads
And cum stains always dry in time
On you and on the backroads
By the rivers of my mem'ry
That keeps you ever perving on my mind