What is 'n'q?
Contraction of "Thank you"
(The "n" sound is made at the back of the throat, like a grunt of acknowledgement, mostly heard from teenage boys.)
The bus driver stops a bit earlier than you asked to be helpful
As you leave the bus, you acknowledge this small favour with "'n'Q", because it is not enough to merit a "Thanks" or a "Thankyou" without sounding like you see it as a life changing action.