This is the 8732nd most frequent Polish word.
rihanny
It seems "rihanny" is not a Polish word. Could it be a typo or a name?
Here, 'rihanny' is used as a plural form of 'Rihanna', indicating multiple persons bearing this name.
Rihanny śpiewają swoje piosenki z ogromnym entuzjazmem.
The Rihannas sing their songs with great enthusiasm.
In this sentence, 'rihanny' refers to performers resembling Rihanna or named Rihanna, used in plural.
Podczas koncertu, rihanny były na scenie.
During the concert, the Rihannas were on stage.
The usage of 'rihanny' here implies a playful mention of Rihannas, either impersonators or symbolic references.