Folks, what's coated with a thin sheet of foil and full of rich goodies inside?
That's right, a caravan!
And Easter time means the Great Grey Nomad Migration is about to set off from its southern hives seeking warmth above the Tropic of Capricorn.
As the rest of us are spending this weekend eating our bodyweight in chocolate, they're packing, putting their homes into hibernation and possibly giving their non-migrating neighbours some good-natured ribbing.
"Do you want our heater? We won't be needing it! How are you off for warm jackets, jumpers and electric blankets 'cause we won't be needing those either! Hooroo!"
Anyway, toward the Equator the caravans trundle, at 20km/h below the posted speed. Which is why frustrated truckies have nicknamed them 'aluminium speedbumps'.
Now, they may be clogging the highways, but they're a mobile goldmine to many communities.
More than one local council has been toppled for messing with the Grey Nomad Mafia. Banning dogs from parks, removing a free camping area or not keeping the toilets sparkling clean can be enough to get your village placed on the nomads' no-go zone and eventual economic ruin. Their sheer volume means there's lots of them spending a little each but it all adds up to a very pretty penny indeed.
Then, as the footy season winds up, an unheard signal sounds and the swarm turns homeward. Their wrinkly skins bronzed and their vans richly loaded with the 3 Ps: Prescriptions, Plonk and Pressies for the grandkids. Until next year ...