Nikko isn't really obsessed with any particular toy, though he does have his favorites. The current favorite is a sock that I crammed a bunch of crunchy plastic trash into and tied a knot in... but he only really plays with it if we are playing with him.
The only true obsession he has is with licking into our nostrils and the insides of our ears. I think I may be able to throw out my q-tips soon, he does such a good job, lol.
Lauren & Nikko