LISTER: At some point in their lives, most people wish they were someone
else. This is going back years, years, before the accident. Kochanski
had just finished with me, and I was feeling really pony. So I went
for a walk in the botanical gardens, and I saw this squirrel, climbing
up and down the tree collecting nuts. And it stopped, and it looked at
me, and I thought: "You lucky little sod -- you like your job, you're
your own boss, and you've got no woman trouble, so you'll never feel as
bad as I feel now. And at that moment, I mean for a split second, I
would have given anything -- _anything_ -- to swap places with him.

CAT: Ah, that's awful, man. When a woman screws you up so bad you want
to become a squirrel.

LISTER: It just made me think that a lot of the time, being human isn't
much fun!

RIMMER: So, Lister, what are you telling us? You're a closet squirrel?
Behind closed doors, you parade up and down with a strap-on bushy tail
calling yourself "Nutkin?"

That scene was one of the first things that came to mind when I discovered furries. Also: Monty Python's (EERILY PROPHETIC) Mouse Problem sketch.