A sausage is just a way of persuading people to eat the most revolting bits of an animal.
It's been tremendously successful, too: I understand that people have been making sausages since prehistoric times. We certainly have a Chinese recipe for goat and lamb sausage from 589BC, and Aristophanes' play The Knights is all about a sausage seller.
On the other hand the Byzantine Leo VI (the Wise) banned sausages following cases of food poisoning.
Not all that wise, then.
Today, of course, there are sausages all over the place, made of all sorts of things it's probably best not to think about too much. English sausages have a habit of exploding during cooking (explosions were especially violent during World War Two, when there was a lot of water added to sausages to disguise the fact that they contained very little meat) which is why we often call them bangers.
The expression not a sausage, meaning nothing at all, is rhyming slang: sausage and mash - cash. So not a sausage originally meant penniless.
Gosh, I'm hungry!
Word To Use Today: sausage. This word is from the Old French saussiche, and before that from the Latin salsus, which means salted.