Rejected Admin joining authentication.

Well I had this idea earlier,the basic premise is that when an admin/mod joins they get asked in chat for a password which they input with "!auth PASSWORD" ,if they fail to input it within 5 seconds they get a kick...or all admins are demoted upon join automatically then have to input the password to be auto promoted back up.
I THINK it should be reasonably simple to code the first implementation,but the 2nd idea with re-promotion I'm not sure would be so easy.

Would prevent little brothers using admin's accounts,people spoofing ID's(VERY rare,but happens) etc