"It stinks. I got it out of the bag before... rancid. It's a quirk of test cricket that we use the same equipment... but it's also a sign of character. It symbolises the hard work, places you've been and emotions you've dealt with.
McCullum shared some fond memories but a generic one summed up his time in the team.
"I'm proud of the evolution of the team and the performances we've started to put up. [I like] seeing a group of guys achieve something over five days with dirty whites, sweaty black caps and a beer in hand looking back on hard work achieved.
"I'm most proud of being able to get off canvas when I've struggled for runs under pressure... when you're desperate for a performance. With strength of character and mind you can do it."
He was thrilled Nicholls had earned his opportunity.
"He's an unflappable guy in clutch moments. He puts the team first, he tries to do something positive and I expect him to have a long and prosperous career."
New Zealand: Brendon McCullum (c), Martin Guptill, Tom Latham, Kane Williamson, Henry Nicholls, Corey Anderson, BJ Watling, Mark Craig, Doug Bracewell, Tim Southee, Matt Henry, Neil Wagner, Trent Boult.
Australia: Steve Smith (c), Joe Burns, David Warner, Usman Khawaja, Shaun Marsh, Adam Voges, Mitchell Marsh, Peter Nevill, Peter Siddle, James Pattinson, Nathan Lyon, Chadd Sayers, Jackson Bird, Josh Hazlewood.