What is the meaning of Glug?

The sound made when a significant amount of liquid is poured suddenly out of something, such as a jug or bottle.

The amount of liquid issued when the "glug" sound is heard.

To flow in noisy bursts.

To quickly swallow liquid.

To pour noisily.

The sound made when a significant amount of liquid is poured out of a jug, bottle, etc., or when such an amount is swallowed by a person.

a peephole, opening, window

(wide open) eye(s)

Source: wiktionary.org