Just curious enough, so is that possible if my reputation drops to zero?
The minimum bound is 1(Thanks for the link gertvdijk). You are a beautiful and unique snowflake, and will melt under the withering heat of criticism if you had a negative score. Stackexchange as such does not have 0 or negative user reputation.
However, to achieve something close to a negative score (a -1) from any positive score, you'd need a string of bad questions or answers. This will result in either a manual suspension by a mod, or a question or answer ban through cold unfeeling machine. This of course, probably will be more annoying than a negative score, and probably means the same thing... other than having a reputation of 1 rather than over - 9000