John Mayer likes women with "caramel" hair and their bra straps on show.

The 45-year-old singer - who has previously dated the likes of Jennifer Aniston, Jessica Simpson, Taylor Swift and Katy Perry - was quizzed on the hair colour he finds most attractive, and gave a surprisingly detailed answer to friend Andy Cohen's question.

Playing 'Pillow Talk' on 'Watch What Happens Live', Andy asked his pal which hair colour turns him on most and he replied: "Caramel with an ombre, like a caramel to dark brown ombre, and like a spaghetti-strap tank top, but then also a bra strap at the same time, and they are sort of like dancing like telephone lines as you're driving."

Earlier in the segment, the 'Your Body Is A Wonderland' singer revealed he last "had a good cry" that morning and quickly named Debbie Gibson as his first-ever celebrity crush.

The 55-year-old presenter then asked John which musical instrument he thought was sexiest.

Laughing, the 'Gravity' hitmaker eventually replied: "What guy could steal my girl with an instrument? And I'd be like, 'That's a cool instrument.'"

When Andy jokingly suggested Kenny G, John smiled and said: "I was going to say the saxophone."

The segment ended after the host asked his guest to describe himself as a lover in three words.

Pausing for a second, John replied: "Takes some time."

Elsewhere on the show, John admitted he is "glad" he and Katy recorded 'Who You Love' together when they were dating.

He said: "Isn't that great? I'm glad we did that.

"It was just at the point where I was saying, 'Why can't I make music from a different era? If I love a style of music and I want to make it, like a genre, why can't I make music that I was pretending was from a different era?'

"And that was sort of like a prototype to Sob Rock. It was sort of like an FM lite radio thing, and Sob Rock is a little more realised.

"But I listen to that every once in a while, and I go, 'I like that song.' And I like the way that she sounds on the song. She got that way of singing down and met the challenge of that song. It was so much fun."