One Direction, Two Direction: The Slope of My Line

(Click on the cartoon to see the full image.)
(C)Copyright 2014, C. Burke.

... Red Direction, Blue Direction . . .
Rising up the chart.

And you know what they say when your slope is undefined, right?

I was working on another verse, but decided to just cut it here.
Suggestions? Please them in the comments.

EDIT: I entered the wrong date, and this published last night with a timestamp of 1am. Go figure.