From Wikipedia: A horse has an infinite number of legs

    A horse has forelegs.
    And it has two back legs.
    Four plus two is six, thus it has six legs
    Six is an odd number of legs for a horse to have
    But six is also an even number of legs.
    The only number which is both even and odd is infinity
    Therefore, a horse has an infinite number of legs

Now we know that the infinite legs are infinitely long.

(Unrelated, but along the same line of silliness from there:

    No horse has five legs.
    Any horse has four legs more than no horse does.
    Therefore, a horse has nine legs.)