Sloth--ok, I get it, and no offense! 
Here's my thought:
Barney=Squirrel (looks deceptively cute and innocent) Hooky=Grizzly bear (ursines getting to be a consensus) Steve=Kangaroo Gillian=Horse (meant as a compliment)
and
Ian=Ring-tailed lemur
(skinny, hyper, with big round saucer eyes. Thought of this before I read the Barney-lemur above, Barney makes a pretty good lemur too I think but more of a squirrel!)
