Los Angeles - Madonna raised $60 000 for charity by showing her bottom to a crowd in New York.
The Girls Gone Wild singer bared her butt and encouraged those watching her to donate to victims of the recent hurricane Sandy - which recently hit the Caribbean and US, causing billions of dollars of damage and leaving many homeless - by throwing their cash onstage.
She told the crowd at the city's Madison Square Garden venue: "I'm showing [my] naked ass for Hurricane Sandy victims."
A concert attendee added to the New York Post newspaper: "One guy threw a $20 bill, and Madonna threw it back and said she wanted hundreds.
"She yelled, 'Is that all my ass is worth?'"
'A split in a thong'
Some front row VIPs also got to see even more of the 54-year-old singer than they had bargained for.
One said: "I was sitting in the first row and when Madonna did a split in a thong it was a Sharon Stone Basic Instinct moment!"
Another added: "Yep, I saw the fern."
The film Basic Instinct famously features a scene in which Sharon Stone uncrosses her legs while being interrogated by police, revealing she is not wearing any knickers.
Fans who had bought $2 500 'Ultimate VIP Package' tickets for Madonna's MDNA Tour concert also had to sign waivers with some particular clauses, including agreeing not to "wander off in any way" during a pre-party or "seek out Madonna or her crew".
They also had to agree "not to engage in any illegal or inappropriate activities" or "acts that are considered disturbing".
Fans at the show on Tuesday were also treated to Madonna performing a mash up of her hit Give It To Me and South Korean pop sensation PSY's cult smash Gangnam Style, with the star joining her on stage.
Watch Madonna and Psy do Gangnam Style here: