Here's a description of Vegemite from urban dictionary:
1. Vegemite
Delicious Australian spread, made from used brewer's yeast. Non-Australians tend to give descriptions of it similar to 'tastes like a mixture of salt and battery acid'. This is because they are wimps, and need to drink more beer, eat more pies, and of course, eat more Vegemite.
The Vegemite Jingle:
"We're happy little Vegemites, as bright as bright can be,
We all enjoy our Vegemite for breakfast, lunch and tea,
Our mummies say we're growing stronger every single week,
Because we love our Vegemite,
We all adore our Vegemite,
It puts a rose in every cheek."
hehe
I don't really know what cruskits are either - a cracker type thing..?