You really should print a code snippet on your shirt written in Whitespace. It will only attract the best programmers out there :)
But if you really need something to start a conversation with a mobile developer, why not try to make them do what they really like to do: help others and show their knowledge. And add a pinch of sugar.
Help me make my phone vibrate!
Or a snipped in LOLCODE (everyone loves cats!)
HAI 1.2
CAN HAS MOBILE_DEV?
VISIBLE "HAI DER!!!1!"
KTHXBYE
Maybe use a graphic as reference for something, older and wiser people will understand.
Or make people stop and think:
Last night I accidentally my whole iPhone App!