Hmm, now I'm starting to think animal prints = something to do with sex. Maybe desiring sex? Or wanting sex but not knowing how to say it? (Santana wears animal prints in Sexy when we learn she wants a relationship with Brittany, Kurt wears animal prints in The First Time when we find out he's been thinking about going all the way with Blaine. And yet, both Sugar and Mercedes wear animal prints all the time...

Maybe it has something to do with attention, both sexual and emotional? Kurt wants someone to pay attention to him sexually, Santana wants more than just sex with Brittany, and both Sugar and Mercedes both just want someone, anyone, to pay attention to them.