I don’t see the harm in adding wild speculation to a three year old thread so here goes.
It was mentioned upthread that the term originated in hobo or carny slang.
The police force is commonly shortened to “the force”. In carny or kayfabe language “The Force” would be either the Fee-uzz-orce or the Fuzzorce. It does not seem a huge leap from “the Fuzzorce” to “the Fuzz”.
So you speak it as an adult?
Yep; I know a Noz who is a Noel. The -z suffix can be added to a consonant that is followed by an ‘o’, as well as a consonant followed by an ‘a’, although ‘o’ is less common.
You can always Google something like “pig” and “Yiddish.” It would indicate that the Yiddish word is chazzer. When you don’t know something, simply Googling can sometimes be your friend.
This I like.
There are several slang languages that distort words in a regular way;
Pig Latin: ‘police’ = ‘olispay’
Ubbi-dubbi: ‘police’ = ‘pubolubice’
and so on.
In Backslang: ‘police’ = ‘ekilops’ (I thought this might be a possible etymology for ‘Fuzz’, but it seems unlikely)
In Carny, or ‘Ciazarn’, it looks like ‘police’ would be something like ‘pe-uz-olice’, but ‘force’ would be ‘feuzorce’, which looks very promising.
http://www.goodmagic.com/carny/ciazarn.htm
The word can also have a metaphorical meaning, though. The Yiddish speakers I knew as a kid used chazzer as somebody who ate greedily or sloppily, or like a pig.
Same with me. That would have been my #2 tip on Googling.