New Metaphor for a New Century

I am proud to announce, in these formative years of the oughties, a new, fresh, appropriate metaphor for the new millennium. A metaphor brought to you by my very own genus Rattus. Ladies and gentlemen may I present to you 'rarer than rat vomit'. 

What's wrong with the traditional rocking horse shit/hens teeth metaphor? I hear you cry.

Well that's just so 20th century is my swift response.

What's so rare about rat vomit? Surely they eat all sort of crap, ergo they must vomit.

Not so. See here. They regurgitate but that's not the same. It does not achieve the projectile nature of the vomit and is mechanically quite different. Regurgitation is a vomit manque, a mere shadow of your projectile hurl. 

So, my rodent millennial metaphor - I thank you.