Title text: The one time I tried, I got hit by a slinky going down at double speed.
This comic is ostensibly two simple line graphs on the same chart. One shows society's expectations, the other what Randall actually felt. The visual joke is that the societal expectation graph is treated like an actual down-moving escalator, with people on it.
An escalator is a moving stairway going in one direction, either up or down. You walk up to it and stand on the closest step to the end you're approaching from. You then stand still while it moves you, and when you reach the end you step off and continue walking. Many people like to treat the escalator like normal stairs, and will continue moving along the steps with the flow as if it were a regular staircase, which increases the speed you reach the end.
This comic is about the urge to step against the flow on a down-moving escalator. You start at the end and attempt to reach the start, trying to keep your upward speed greater than the downward speed of the escalator, so that you reach the beginning.
The title text refers to the Slinky toy, a coiled spring that is designed to go down stairs by itself in an amusing manner. Since the Slinky is moving with the flow, its effective speed is doubled. A normal Slinky is very small and would not be able to halt an average human being through its inertia, but it could tangle up in their feet or otherwise trip them up.
- [Graph with y axis titled "Urge to try running up the down escalator", with "weak" by the bottom and "strong" by the top. x axis has every two years labeled and every year signified by a smaller mark, which stops at 24. A red line with "What I was supposed to feel" with points at every line rises, peaks at 7 years old, then falls "tangent graph" shaped until the end. Along this line are shown various stick-figures at 12, 14, 20 and 24. A second red line runs "What I've actually felt" which stays consistently high.]