Tim Cook joked that people should just recycle their phone if it's not an iPhone

Vimeo/GW Media Relations

Apple CEO Tim Cook holding an iPhone

Cook spoke about Martin Luther King, Jr, working with Steve Jobs, and meeting President Jimmy Carter.

But Cook couldn't resist making a little joke aimed at the people in the audience who were using Android phones.

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"They've asked me to make a standard announcement ... about silencing your phones," Cook said. "So those of you with an iPhone, just place it in silent mode. If you don't have an iPhone, please pass it to the centre aisle, Apple has a world-class recycling program."

You can watch Cook make that joke around one minute into the video here:

That wasn't the first time that Cook has joked about competing smartphones. At the company's 2014 WWDC conference he told attendees that 130 million Apple customers who bought one of the company's products in the last 12 months were first-time Apple buyers.

"Many of these customers were switchers from Android," he said. "They had bought an Android phone, by mistake, and then sought a better experience. And a better life. And decided to check out iPhone and iOS."