Banhammer

From OLSEncyclopedia

Any member of a web site with the power to ban users is said to wield a Banhammer. If you get hit by this banhammer, you are banned. Depending on where you're hit, the ban will be a different length. If it's out on the extremities, the ban will likely be short, however, a full force blow to the head often results in a permanent ban. This attack cannot be blocked, but can be evaded by using a proxy to register a new account. You will never be subject to this attack if you follow forum rules.

Banhammer is sometimes written as b&hammer.