My brother's 3 darling daughters were like stair steps following my own three kids, the first two of whom are boys. All are grown now. I guess boys just have less couth than girls, because a single incident resulted in my younger son being known for years to these cousins as "The Boy Who Burps by the Door." Apparently the little girls were quite impressed or even alarmed by this legendary burp. The boys, junior high age at the time, would swallow air and have burping contests. They got pretty accomplished at the art of willful burping. (Don't look at me - they learned it from their dad!)