This is a fun expression, it's even more fun to investigate since both those words pretty much sound nonsensical, so there's that extra layer to uncover.
I'm not sure this will be as popular as last weeks investigation on the origin of the Expression Bum F#@% Nowhere.
Source
No, it has nothing to do with Urination Fetish Kit pictured above that I found while googling for this piece.
Expression
The whole kit and Caboodle; not sure if this one is worldwide or often used everywhere but it simply means you a lot of things or everything you need for a task. It can be used in reference to just about anything.
You may say "Wow, the kid's got the whole Kit and Caboodle for Christmas." or "Crap, why'd you pack to much stuff? You have the whole kit and caboodle"
It also has nothing to do with that really crappy cat food (based on the ratings in the source) in the photo above.
Origin
Mostly we have to define Kit and Caboodle to make this make sense. We'll start with kit since that's the easy one.
Certainly nothing to do with Kitt, from Knight Rider.
Kit
This is one I actually use, since this term is still often used in the army in reference to any supplies, equipment or gear you may use. Like a toolkit. You'll often hear 'go draw kit from the QM', or 'pack all the kit your going to need'. I even still call my shaving kit, my ablutions kit which gets alot of sideways looks.
Caboodle
This one is a bit older and has totally fallen out of regular use. In fact the original form of the word is actually just boodle and it's felt that the 'ca' was just added to help with alliteration for this expression. (I mean it does sound better than "kit and boodle".) Anyways a 'boodle' is an old English word meaning a bunch or bundle. Through it's history is was used to refer to a group of people or also a stack of money, but it's been a long lost word for many years. It seams to have faded from use in the early 1900s, but despite this the expression has survived.