Einen Kater haben
Literal: to have a tomcat. Actual: to have a hangover.
Literal: to have a tomcat. Actual: to have a hangover.
This phrase means that someone is suffering from a hangover. It originates from the medical term 'catarrh' (mucous inflammation), which 19th-century university students jokingly pronounced as 'Kater'.
Idiom