Highly unusual methods (also HUM) is a class of contract bridge bidding systems defined by the World Bridge Federation. Usually these are artificial systems that require advance preparation to contend with, and are restricted to the highest levels of tournament play in most locations. These systems are designated by a yellow sticker, and are more regulated than brown sticker conventions.

The current definition of the WBF lists the following HUM Policy:

A Highly Unusual Method (HUM) means any System that exhibits one or more of the following features by partnership agreement:

With the exception to the above being an opening of one of a minor in a strong club or strong diamond system.