Probability is not defined for negative values. Probability is defined for all x, where 0 < x < 1.
I'm going to assume you're being sarcastic in that comment though.
I think he meant to convey less than one percent, but accidentally typed less than zero percent. Such as 0.5% or similar.
I was speaking as a counterpoint to the naysayers, but in their original tone and knowledge of statistics. Please see my earlier posts here and here in this thread to understand that although my humorous comments may have a subtle "whoosh" sound for some, at least on statistics I can make up some pretty believable stuff.
Another pool operator describes why their pool is only set up to transfer accuracy down to bitcents here [forum.bitcoin.org] - it is to prevent you from losing the money through digit truncation in the client [BitCoin Git Repositories]. The code to zero out the first six digits of satoshis in each transfer was finally removed in the mainline client code only this year, and there may be several forks or mods circulating and in use based on this older code that would still outright discard this penny's worth of bit dust.