The umbigada (pictured above) is one of the most traditional and characteristic movements of many Brazilian dances and is called semba in the Quimbundo* language of the Bantus of Angola. The semba gave birth to the jongo which in turn, gave birth to the modern-day samba. For reasons unknown, the jongo employs only a feigned umbigada.
The umbigada itself can be described as a light hit or blow, that is given with the belly during circle dances which signifies an invitation or a daresay used by the dancer to invite her successor into the centre of the circle. In the fandango and in the lundu in Portugal, the umbigada has the same purpose, as also occurs in the dança da punga of Maranhão and in the cocos de roda or bambelôs and even in certain sambas. The batuque paulista already employs the umbigada although not as an invitation for the substitution of who is singing in the circle.
* – Interesting to note that the other name for the Quimbundo language is Mbundo, which is the origin of the word bunda (butt in Portuguese). See comments.