the term has too be a genericized trademark and as such occurs as conversational term for any personal cooler. It is super popular at Australian barbeques, picnics & sporting cases for keeping food and drinks cold.

Cultural References
There are the total of information to esky within Australian popular culture: Esky lids occurs as dismissive slang term surfers give body boards. A few Australian songs that include information to 'eskies' come: Paul Kelly's Roll On Summer - "The sweet metal taste of VB, Straight from the ice cold esky". Jebediah's Country Holiday Song - "Come and take a drive out of the city, packed some smoke and some wine in an esky".