Watch out Dr. Ruth and Sue Johanson -- there's a new sex guru in town and she's a lot less wrinkly, too!

After her show at London's O2 Arena on Sunday, Rihanna hit up the club Whisky Mist in order to celebrate her brother Rorrey's 22nd birthday. While there, the 'S&M' singer gave some safety tips for the bedroom, according to a report from The Sun.

Before letting her fans in on some helpful sex tips, Rihanna led her and Rorrey's posse in a 'Happy Birthday' sing-along. Once the group finished the song, RiRi definitely had her little bro blushing when she said, "I left home at 16 and had to learn to look after myself. Always use a condom."

Later on -- after 15 bottles of champagne, six bottles of vodka, and Rihanna's advice on the wonderful world of prophylactics -- Rihanna, Rorrey, and a posse of the birthday boy's friends and female admirers went back to the 'What's My Name' singer's suite at the Savoy hotel.

"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," a source tells The Sun. "They had a great time and she treated them like kings."

We bet that was one hot and heavy hotel party!