The present invention provides a spout for use with containers, particularly portable fuel containers. The spout has a slide assembly physically coupled to a proximally positioned plunger. The slide and plunger may be moved in tandem to variably control the flow rate of liquid or fuel through it. The spout may have a main body portion and a nozzle portion, and an exit opening at or near the distal end of the spout. Passageways within the spout are designed to encourage segregated and orderly flows of liquid/fuel and air for control and increased flow rate of liquid/fuel from a container. The spout may further have a holder(s) on the side of the spout for contacting or engaging a structure or surface of a container, tank, etc., being filled, to help hold and properly position the spout to avoid overflow during use. Methods of assembly and operation are also provided.