Don't be modest! Y'all sound good!

One conference I went to started (early on opening morning) with the presenter telling us that we couldn't learn unless we got out of our comfort zone - and then asked for volunteers to come to the front and SING (in front of about 250 people). Upon finding no volunteers, the presenter then picked four victims from the audience at random, insisting (over their objections) that they had to come to the front & sing. Once the four had assembled (looking quite sheepish), the presenter gave them a song to do, and they burst into song.
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It was immediately obvious that we'd been had!! The four were a professional barbershop quartet that the presenter had planted in the audience!

The singers entertained us for a few minutes and the conference began on a great note (no pun intended). I've never forgotten that trick and plan to use it myself sometime soon.