Tom Waits reveres Keith Richards -- "there's nobody in the world like him," the eccentric singer-songwriter says of the Rolling Stones guitarist -- so when Waits began to pen songs for his new album, 'Bad as Me,' he recruited Richards to co-write some tunes. None turned up on the final product, though -- perhaps because neither could actually remember the music that they had improvised together.

"We wrote songs together for a while and that was fun [but] he doesn't really remember anything or write anything down," Waits tells NPR's 'Fresh Air.' "So you play for an hour and he would yell across the room, 'Scribe!' And I looked around. 'Scribe? Who's the scribe?' And he'd say it again, now pointing at me."

"I was supposed to have written down everything we said and dreamt of and played," continues Waits. "And I realized we needed an adult in the room. I've never been the one that one would consider the adult. It was an interesting dynamic."

Richards isn't credited with writing any of 'Bad as Me,' but he did end up playing guitar on four tunes, including first single, 'Satisfied.' If the song's title doesn't provide enough of a hint, the lyrics includes a couplet that could be considered an homage to Richards and his Stones bandmate, Mick Jagger: "Now Mr. Jagger and Mr. Richards / I will scratch where I've been itching."

Richards -- who also provides vocal harmonies on a tender 'Bad as Me' bawler titled 'Last Leaf' -- first hooked up with Waits back in the '80s in a New York studio when Waits was recording his 'Rain Dogs' album. "[Keith] came down with a semi-truck full of instruments and a musical butler and we played until very late, he played on four or five songs," Waits says. "We've stayed in touch ever since then."