Britney certainly hears it though - and the entire auditorium hears her response: "F**king a**hole" she replies without breaking her stride, and then launches into the song as if nothing had happened.
However some fans who were at the show insisted on Twitter that what she said was plural - "F*cking a**holes" - and that she was addressing the crowd at large.
The outburst came after the Toxic hitmaker had asked the audience if they "want one more song?" - which appeared to get a positive response - but some online suggested she may have heard at least one answer she didn't like.
Britney has been accused of miming on stage before, but at least fans can now vouch that she definitely has her microphone switched on.
Her manager Larry Rudolph revealed in an interview last year that she does mime part of the time simply because it is physically impossible not to.
"To put on the show that she puts on, it's virtually impossible to sing the entire time and do what she does," he said.
"She's singing on every song, basically, when she has the ability to sing. There's no way you can dance for 90 minutes straight and sing the entire time."
Iggy Azalea and Britney Spears are seen on set of their music video. Photo / Getty Images
Meanwhile fans are eagerly awaiting Britney's upcoming collaboration with Iggy Azalea, Pretty Girls, due for release on May 5.
