Riri gives flawfRih sex advice!

And it appears that the Bajan singer is prepping herself for the role — after she gave out naughty advice to punters in a West End club.

Hours after her gig at London's O2 Arena on Sunday she headed to Whisky Mist in Mayfair to celebrate brother Rorrey's 22nd birthday.

After grabbing the mic and leading a celebratory singsong, she then took the opportunity to deliver her version of the birds and the bees.

She said: "I left home at 16 and had to learn to look after myself."

"Always use a condom."

The machine in the gents' must have made a killing.

Maybe her words of wisdom were aimed at Rorrey, his mates and the group of girls crowding around them. At the end of the night, following 15 bottles of champagne and six bottles of vodka, Rihanna rounded up the party and took them all back to the her suite at The Savoy hotel.

And you can bet they didn't go there to watch CNN on the telly.

A source said: "Rihanna is the best big sister.

"She sorted for all these girls to accompany her brother back to her hotel, along with his friends too.

"They had a great time and she treated them like kings."

Meanwhile, the singer's security were left needing new trousers after they suffered a scare during the afternoon soundcheck of her O2 gig.

While circling the arena they spotted two dodgy-looking geezers with guns.

But before the police were called it was pointed out that the two characters were actually hardman actor Ray Winstone and rapper Plan B filming the new big-screen version of TV classic The Sweeney.

The constant screams of "Shut it!" must have given their identity away.

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