Duck,

A stubby is a small bottle of beer.

They have to be small in Australia since the average Aussie is well known to be unable to hold his liquor.

A stubby holder is, as Belle said, a neoprene sleeve with a bottom on it that you fit over your beer to keep it cold.

Also necessary in Australia since it takes them a while to drink one of those small bottles.

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Faster than a speeding puck...