Much to the chagrin of my flatmates, I still have quite a few plushies from when I lived at home(and some from more recent days). I cuddle with them while watching television, several join me on ski trips, they even hang out with me when I'm doing homework. They are an almost constant presence when I am around.
For some, however, they would be deathly afraid to admit even owning a plushie, much less carrying one around in public. Its as though there is something taboo about it, something wrong with it. So they get rid of all of their plushies, or stuff them in a box in the attic, or find some way to keep their friends from seeing them.
In my travels I found that nobody really cares. When I started wearing a plush wolf back-pack while teaching, I didn't get any negativity. Even some of the macho, cooler-than-thou snowboard instructors thought that it was cute. My roomies don't care that I sleep with a german shepherd, or that I cuddle with it while watching T.V., they just wish I wouldn't leave it in the living room, lest someone think that it's theirs.
I really think the embarrassment developed because we were all 13 once in our lives, a time when we were 'grown-up' and didn't want to be children anymore, so we tried to get rid of all the little-kid stuff in our lives, and openly mocked and derided anyone who didn't act like all the cool older kids. Stuffed lions weren't cool anymore, it was all about playing videogames with the 'm' rating and making fun of third-graders.
Now, when as head out into the world, we look down at Mr. Bear, and despite how comforting he is, we still hear the taunts and jeers of millions of 13 year-olds. We've conditioned ourselves to think we will be made fun of for appearing childish. We do this to ourselves, the only one who cares if you still have stuffed animals lying around is you. Your room-mates don't care, your boss doesn't care, your professors don't care. If you have a favorite plushie that you still cuddle with, stand up and be noticed, because nobody cares.