It comes from a song, "Be kind to your webb-ed footed friends", but you're right in the us vs. them kind of language here, and the patronizing tone. WisCon has been really good about saying "those of US with impairments" and such, which has made a huge difference.

Here's the song, which yeah, is a kids' song:
http://www.youtube.com/watch?v=HxUH7Vt3v-A