Characters
I’m up and down more often than a pair of kangaroos in the mating season!
— Kryten ‧ Red Dwarf

Behind the line May contain spoilers.
Our reading
An editorial interpretation.
The speaker exaggerates how often they go up and down by comparing themselves with mating kangaroos. The image combines bouncing movement with a bawdy suggestion. Whether the changes involve movement or circumstances, the complaint makes their repeated shifts sound exhausting and comically excessive.
Context reviewed