What is Not My Pigeon?
1.
Not of material interest oneself. Not one's business. Not an activity one would typically engage in under normal circumstances.
"Leeroy, ya djam fool buoy. Get yourselt oder 'ere an' have a tug on dis 'ere crack pipe."
"That's jolly decent of you Winston my dear boy, but freebasing crack cocaine is really not my pigeon. These days I stick to mainlining skag and the occassional speedball."