Drink like a fish
Definition 1 of 1
Pro Tip 1/3Informal Usage
Used in casual conversation, not suitable for formal or professional settings. 
Whenever Mike hosts a barbecue, he drinks like a fish.
Pro Tip 2/3Metaphorical
It's a figure of speech comparing a person's drinking to how fish swim in water, implying excess. 
On his birthday, John drank like a fish; he didn't leave the bar stool all night.
Pro Tip 3/3Negative Connotation
The phrase often implies a judgment or criticism about someone's drinking habits. 
At family gatherings, Uncle Jerry drinks like a fish and becomes the joke of the night.