An agitator may include one or more members adjustable between an expanded configuration and a compressed configuration. When the one or more members are in the expanded configuration, the agitator in a first set of two orthogonal dimensions is larger than an opening having a predetermined size. When the one or more members are in the compressed configuration, the agitator in a second set of two orthogonal dimensions is smaller than the opening having the predetermined size. The one or more members are biased to the expanded configuration in absence of external force applied to the one or more members. In use, the agitator may be inserted into a container through a neck of the container in the compressed configuration. The agitator may expand within the container so that the container does not fit through the neck of the container.