Rihanna -- New Guy Gets Taste Test

Rihanna went all Cara Delevingne on fashion photographer Steven Klein at Monday night's British Fashion Awards.

Klein posted one photo -- with RiRi's hand on his face and her tongue in his ear -- with the caption, "Me+Rhianna being Naughty at the British Fashion Awards." He doesn't say what the equals.

Rihanna's attention was momentarily diverted by a blunt ... the girl has priorities.

As for Klein, he's shot big ad campaigns for the likes of Calvin Klein, Dolce & Gabbana, Louis Vuitton, Balenciaga, Alexander McQueen and Nike.