I remember a time when I did someone a good turn and they said 'Thank you for saving my bacon'.
I've said the same thing myself too but have often wondered why it refers to bacon rather than any other meat or indeed why it refers to meat at all.
It seems that the phrase was used as long ago as the 17th century. Here is a quote from 1654 in 'Momus Elenticus':
"Some fellowes there were... To save their bacon penn'd many a smooth song."
The phrase has a similar meaning to 'saving one's skin' so it refers to escaping from harm.
The reason that it speaks of bacon is simply that way back then, bacon meant all of a pig's meat not just those delicious crispy rashers which I like to eat in a sandwich with lashings of butter, ketchup and Worcester sauce.
Surely this has to rate as one of the greatest snacks of all time. In fact I am drooling at the thought and having to hold back from going off to make one now
... but I digress.