This idiom is used to describe the situation when people promise good things for the future that will never come.
- “Don't worry everything will be fine because we are going to win the lottery tomorrow”
- “Be seriously will you, you always promised jam tomorrow”
Be very careful when using this idiom as it is specific to the north of England! While it might be known in all parts of England it is not widely known in other English-speaking countries.
It is very important when learning English to use the assistance of a professional native speaking English teacher, the kind of teacher you can find at the online English school www.SmartLanguageSolutions.com