Milk

Milk is a Food item that replaces models/props_junk/garbage_milkcarton002a.mdl on any map. Drinking Milk knocks the player down for 10 seconds. It can also be obtained through Fishing, the Splinter Box, Jake's Khakis, the Dimension of Gluttony, being on the Fan List, Random Zombie Loot Drops, RTD, and the lowest tier drop from the Guerilla Gorilla, SCP-173, Drill Bot, Skeleton Centurion, and Traffic Light.

Trivia

 * If you have the CAT Attribute, drinking Milk will not knock you down and the water power will be increased to 100.
 * Milk is supposed to give the "confusion" Screen Effect. However, this is disabled due to the Screen Effect Bug.
 * If you have the Survivalist Attribute, drinking Milk will not knock you down.