barrel laughter is an irrepressible laughter and has a bit to do with American slavery in our culture that you Steve are lucky enough not to share.
Slaves with boisterous personalities and wanting to laugh or shout often had to stifle their outbursts by the use of the “laughing barrel.” It was not by choice but this is what they were trained to do on the plantation. The black house of praise during this time also used “shouting barrels” when the slaves would steal away at night for church services. The slaves would stifle the noises they wanted to make by holding their heads over barrels (sometimes filled with water) to keep slave patrols and their white plantation owners from hearing them.

Poet Maya Angelou was quoted saying, “the slaves were not allowed to laugh on many plantations. When the urge to laugh became irrepressible, the slaves had a ‘laughing barrel’ into which they would lean way down, with the pretext of getting something, and laugh. The slaves would then go back to whatever it was they were doing.”

The kind of laughter heard at the UN was the kind that was trying to be stifled without success.

Steve my word choices are often more pointed than it may appear to you.