Who knows! But if you're caving already, you're not gonna survive the others.
[ Okay, at least only one other, but the point still stands. ]
Kinda! Kittens or puppies work well too. Also don't call him a hamster to his face, it generally ends with you either getting bit or giving his apparently-patented Death Glare. Yoon-sung learned that one the hard way when he caught us having lunch together at one point.
It was his own fault on that one, so I'm in the same boat, honestly.
Honestly at this point I'm surprised he hasn't tried breaking in to see the girls at my place. But yeah, cute animals are a huge weakness for him. Go forth and flirt with him, make him weak in the knees, etc.