About lemon juice
The juice from a fresh lemon, which is the best form of lemon flavor. Bottled lemon juice can be substituted if fresh lemons are not available. It can be squeezed manually or bought commerically.
Jif is a brand of lemon juice sold in the United Kingdom and Ireland, by Reckitt & Colman. Notable for its unique plastic lemon containers usually known as "jiffy lemons" or "jif lemons", it is also sold in bottles. A well-known advertising campaign introduced the catch-phrase "Jif lemon day (don't forget the pancakes)", due to the popularity of lemon juice (and specifically Jif) with pancakes on Shrove Tuesday.