Not sure, but yo mom was the best thing BEFORE sliced bread.
2 problems with that response.
(1) Sliced bread was first sold in 1928. My mum isn't that old, therefore, it's an impossibility.
(2) Assuming she is that old for the sake of argument, well, I think you can see where I'm going with this.
The answer is quite obvious, something to put on the bread. Or in other words the Sandwich.
I have actually done some research on the subject:
Wooden legs, stout, second wives, the King James Bible, iron bridges, public executions, hot acorns at the theatre, the London Bridge and Queen Anne's breasts are among the things that have been historically referred to as 'the best thing since'.
During my research I also stubled across a few things considered 'the worst thing since': The Black Death, Welsh prostitutes, that b*astard Cromwell, France, the French, French anything, German anything (anything foreign to Britain in fact), window tax, the Industrial Revolution, and my favourite one of all 'the law against buggery'.
Praise the lord for useless trivia.