In Russia we say "spherical horse" instead of "spherical cow". I suppose that's because the russian translation of "horse" ("конь") sounds somewhat similar to "

In Russia we say "spherical horse" instead of "spherical cow". I suppose that's because the russian translation of "horse" ("конь") sounds somewhat similar to "cow", and the translated phrase has the same rhythm as the original one. With "cow" ("корова") the translated phrase turns out to be a little tongue-twistey.