Can be one of three things;
a huge bearlike creature that only really eats bamboo and enjoys living in solitude, hence the depleting population.
the second refers to the big police vans that take you away when you and your "associates" have been rather naughty. Pandas are also called: meat wagons, paddy wagons and I think many things ending in wagon
<Rich> I thought a meat wagon only referred to an ambulance. It really only makes sense like that. Paddy wagon has its etymology in that they were frequently brought to the scene by irishmen with badges of authority, sticks of poking, and guns of hole-punching. Meat wagon is for carting around meat, such as living or non-living slabs of people, to whatever local hospital can take them. Paddy wagons are also called Black Marias.
<Womble> well in the lovely london met police some precious civilians fall over drunk after 2 shots of vodka and a nice MillwallBrick to the head, big wusses, hence meat wagon, don't matter how they get in there they'll end up slabs of meat, but each to their own...
a car with the engine of a lawnmower (see FiatPanda )
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What a happy chappy this one is