I've often joked that the phrase "excuse me" doesn't exist in Australia. Nine times out of ten, when there are groups of people standing around in social settings (regardless of nationality), they become completely oblivious of the other people around them. If you encounter such a group in the US, you say, "excuse me" if you are trying to get by and then you do a little dance around one another. If you say, "excuse me" to a group of Australians, they will look at you like you are from outer space and there's no little dance, so trying to get past such a group becomes very awkward. I've tried to observe the verbal and visual cues taking place in this scenario to better understand what it is that I'm doing wrong. The best I can come up with is that if you are a man that is trying to get by a group and it is a women that is mainly blocking the way, then you grab her by the hips and move her past you while saying, "sorry, love" and if it is a man that is mainly blocking the way, then you grab him by the shoulders and move him around you while saying, "sorry, mate." If you are a women and walk up to such a group, then everyone parts like the Red Sea and you walk through without saying anything at all.
I'm too chicken to test this theory, so it will remain an Australian cultural enigma.