From BillR, who comments “Ok, I know who D.B. Cooper was, but the rest of it is beyond me.” Yep, me too.
For those who don’t know who D. B. Cooper is: https://en.wikipedia.org/wiki/D._B._Cooper
I find the hovertext even more confusing than the cartoon itself: “The only other person to walk by was a linguist back in the ‘80s, but she just spent a while directing the phrase ‘help me down’ before getting distracted by a squirrel and wandering off.”
(Edit: the hovertext actually says “dissecting,” not “directing.” So that’s much less confusing.)