Nothing makes you question a friendship more than going over to a friend's house for dinner only to realise they still buy the glass Heinz tomato ketchup bottle rather than the modern squeezy variety that has transformed our dinnertimes.
Who are these people?
So, in those moments of uncertainty, what you need is a fail-safe solution to remove the last splodges of Ketchup from the bottle to ensure your chips and burgers get a generous coating of the red stuff.
The answer? The number 57.
A spokesperson from Heinz told the Mirror: 'The sweet spot to tap on the Heinz bottle is the embossed 57 on the neck.
'All you need to do is apply a firm tap where the bottle narrows, and the ketchup will come out easier.'
Mind – blown.
Some of you might be thinking 'well, that's obvious', and if so then where was our memo?
However, if this hack is new to you, you're not alone as 89% of people are clueless about the 57-slap hack, according to the Heinz website.
Go long and prosper, ketchup lovers.