I did this with a friend once. 3 weeks later his phone got a firmware update and his coins disappeared.
Today when I send bitcoin to friends, I always generate a passphrase-based address (aka brainwallet) for them first and send the coins there. If they end up getting interested in bitcoin they can eventually send their coins to their own wallet/client/brainwallet and secure them. If they don't have any interest or lose their wallet/password/etc, I can always recover the coins with a simple passphrase and nothing is wasted.
There's a nice fun factor to walking up to a buddy and saying something like "John Smith smells like old socks <phone number>", followed by "I just gave you 2 bitcoins!"
(yes I know that's not a good passphrase but it's good enough for a small amount to illustrate the concept)
For easy brainwallets, try http://bitaddress.org
and enter any string of text on the Wallet Details tab.