Definition

An acronym standing for 'Agreed Huge Time'—a shorthand way to express emphatic agreement with whatever absurdity someone just stated.

Example Usage

Person 1: 'That concert was terrible.' Person 2: 'AHT, worst two hours of my life.'

Source: Urban Dictionary (https://www.urbandictionary.com/define.php?term=AHT&defid=17379440)