Pilot: "It's not my first day in New York. It's not my first day in an aircraft."
From the Irish Times:
The Aer Lingus plane referred to as "Shamrock 104 Heavy" throughout the recording had gone down the runway southwards, and was intending to turn left across the Atlantic and towards Ireland.
The pilot saw a storm upon take off to his left that he deemed unsafe and so carried on straight to await further instructions.
While the pilot thought the storm was unsafe to fly through, the air traffic controller became agitated telling the pilot no other aircraft had deviated from the requested course.