It's disappointing to see so many negative posts here. For those saying that there's no harm in making jokes about such a "low hanging fruit", note how so many people in this thread have made posts along the lines of, "What's a furry? From the posts here, I'm guessing it's some sort of sex thing." By making these remarks, you're already giving others strong negative impressions.
I'm not a furry myself, but I can understand the general idea of finding appeal in the aesthetics of combining human and animal forms to create something perceived as cute, and following that aesthetic to create art, and yes, costumes. Taking the example of Zootopia, a lot of work had obviously gone into designing the different anthropomorphic animals, and how the natures of the animals can be reflected in their personalities and actions. It's hard to say if the designers of Zootopia identify as furries (probably not), but a furry is simply someone who finds appeal in that aesthetic and identifies as such. From that point, you do get people who use the aesthetic for erotic art and even sexual acts, and that can obviously result in revulsion from those outside the community (or even within). That initial revulsion is understandable, but even if it was the case that every furry finds appeal in the sex aspect of the fandom (which they don't, as attested by by posters in this thread), it is a fact that several posters in this thread and many others have repeatedly said they don't like jokes about furries and sex, especially ones implying pedophilia. I feel it would be best to respect their wishes.
Also, those saying that they used to irrationally hate furries but don't anymore because they irrationally hate bronies now, not really an improvement.