That's not explicitly supported because it's dangerous and easy to screw up. If your two wallets get out of sync you can create invalid double spends that may be hard to recover from.
If you're absolutely sure you want to do this, you can - the latest versions of the Android "Bitcoin Wallet" app from Andreas Schildbach allow import of private keys. So create some on your laptop (eg, with MultiBit), then import into the Android app, tell it to resync and you're done. But don't say we didn't warn you.
I agree with the warning, especially with the addition that it is probably unwise to keep access to your whole wallet on a mobile device. Phones get stolen, other apps abuse their permissions, and there's a good number of situations like law enforcement encounters or trips to the emergency room for an extended hospital stay where your device can be physically accessed by other people.
Keeping more than a token, or useful but expendable amount of bitcoins on your mobile device responsibly means doing quite a bit more than most android users to secure your phone. Oh, how I wish there were a decent Blackberry app for bitcoin. Most of the world has passed them over, but for the security conscious few things lock down as easily for the price as a cheap Blackberry curve.
Then of course backing up your mobile's keys in Armory (preferably separated from your main wallet) can keep your coins safe if your phone succumbs to a worst case scenario.
