Hi Mike
I think you will find that this is a humorous phonetic way to say 'sausage'. There are a few possible sources for this that I can think of:
1. In English, it just sounds funny.
2. When you are trying to be a ventriloquist but are not very good at it, this is what the word 'sausage' sounds like.
3. Many years ago, there was a popular English TV show where a dog could 'speak' a few words. Here it is:
http://www.youtube.com/watch?v=DrX-Yv8gLB8. For some years afterwards, if you said the word "shoshages", everyone knew where it came from and knew it was a joke.
In the contex that you found it, an 'oral shoshage' is probably a way of mangling words so they sound silly.