Wikipedia
Umbigada
Umbigada (from Portuguese umbigo, " navel") is a dance move in various Afro-Brazilian dances. Sometimes translates as "belly bump" or "belly blow", it is performed as follows: a dancer opens her arms and extends her navel towards another dancer. The bodies of the two dancers may or may not touch.
It is seen as a "basic feature of many dances imported to Brazil and Portugal from the Congo-Angola region": samba, fandango, batuque and many others.
It is commonly used as an invitation to dance, e.g., during samba de roda (" samba in circle"). However it may also constitute an element of the dance itself.