A "gallon jug" is a large container that can hold a measure of liquid called a gallon. It is usually made of plastic or glass and has a handle and a cap for pouring and storing liquids. Full definition
They carry gallon jugs of water around everywhere they go, stay in the gym for 2 + hours just to «hang out,» and I'm pretty sure one of them wore a sleeveless hoodie to a funeral. (fitmole.org)
I was assigned to filling gallon jugs with water while Aunt Pearl arranged enough small jars to give the family for drinking. (rachelheldevans.com)
One customer may want to order barbecue sauce in gallon jugs while another prefers small packets that it can hand out to its customers, she adds. (fooddrink-magazine.com)