Okay, here's a couple that I thought of. Im speaking as an Aussie (now living in the US) so when I say "we", I mean Australian's say it this way .....
Also different regions in Australia have their own slang, so what I grew up saying (as a Sandgroper) wasn't necesarily what the kids in Sydney were saying ....but you can bet it was just as weird.
Food Related
We say icy pole, here it's a popsicle, jam is jelly and jelly is jello
We refer to pop or soda as "cool drink". Lemonade is like Sprite or 7up in Australia, here it is not carbonated.
As someone mentioned, we call dinner "tea" and dessert is "sweets". Tomato sauce is ketchup, chips are french fries, chewy is gum, and an entree is a starter or appitizer, here it's the main course. Also if you order a salad here it usually comes before your main course, In Australia it comes with the meal. I'm still not used to that!
Okay, general stuff...
The rubbish bin is the garbage can, the pavement is the sidewalk, a pram is a stroller, the loo or toilet is usually referred to as the bathroom or restroom (just a note - in Aust. a bathroom is only called that if there is a 'bath' in there), we definately don't refer our bum as our fanny, that's something altogether different
On your car, the boot is the trunk, your bathers/cossie/togs are your swimsuit, if your pissed, here your mad .. in Australia your drunk (or better known as "off your face"), if your agro, your mad. We call a cigarette a "***". An "esky" is a cooler, "bikkies" are cookies, a "kip" is a nap, a torch is a flashflight.
Okay just a few funny saying that I grew up with and didn't think they were weird until I moved here and was told "they definately are strange"
"I'm easy" just means I don't care what we do/which way we go, I'm being agreeable ... it doesn't mean your gonna get lucky!!
If I "spit the dummy", I'm having a temper tantrum, usually rectified by DH saying "I'm easy" and letting me get my way.
"Beg yours?" means I didn't hear/understand you, please repeat, as in, "I beg your pardon".
"Flat out" means I'm really moving fast.
"Flat out like a lizard drinking" is even faster.
If Im "having a gander", I'm just looking .... if I can't look away, then I'm being "a sticky beak".
A "dag" is a funny term of endearment to someone being silly. (Don't worry that it really means the poop stuck on the wool of a sheeps bum).
Okay and the last few are probably not that common, but sayings my Dad still says every day.
"Lets hit the frog and toad" of course that means lets get going/hit the road
and "Let me have a butchers hook", it just means he needs to have a look.
See ya round like a rissole
(okay a rissole is a small meat ball)