Phrs./Exclam. A phrase expressed to denote incredulity at a person's statement or behaviour. Often heard pronounced in mock Cockney as 'aving a larff. E.g."You're having a laugh! There's no way I'm loaning you money with your reputation with not paying debts."
HAVING A LAUGH
Meaning of HAVING A LAUGH in English
Slang English vocab. Английский сленговый словарь. 2012