One of the best things about the Jimmy Fallon show — maybe the best thing — is that it’s a test of ingenuity every single day. It sent me back to the days of working with Dave Chappelle. But that show was brilliant guerrilla comedy; it happened on the fly and then some. The Fallon show is a day job in the best sense. We’re in by noon and gone by seven, and in between we make a show. It’s highly structured, and as a result, the opportunities we have for creativity are really distilled: not reduced at all, but disciplined, forced into existing forms and packages. “Freestylin’ with the Roots” is one of the highlights for us. One of the others is the walkover.

The walkover, or walk-on, for those who don’t speak backstage, is the song that the band plays as a guest comes out from behind the curtain and walks over to the host’s desk. Once upon a time, maybe, it was straightforward, a little musical cue or song associated with the artist. But then came Paul Shaffer’s work on “Letterman,” and the walkover became its own little art form — an obscure musical reference that the audience (and sometimes even the guest) had to decode.

From the beginning, I wanted the Fallon walk-ons to be classics of the genre, the talk-show equivalent of video game Easter eggs. When we had Salma Hayek on the show, rather than play “Mexican Radio” or even “Salmon Falls,” we did some Internet research and unearthed the theme song from the first Mexican soap opera she ever starred on, “Theresa.” She knew it faintly at first, or at least knew it was something she should know, and her eyes went wide when she figured out what it was. When Edward Norton was on, promoting “The Bourne Legacy,” we played Patrick Hernandez’s 1979 disco hit “Born to be Alive.” And we thought we had a great left-field pick when we played the Dave Matthews Band’s “The Space Between” for football player Michael Strahan, but somehow he knew it immediately. Howard Stern once came up to me during a bathroom break, confused, to ask me why we played this disco song by Bell and James for his wife, Beth Ostrovsky. “She’s from Pittsburgh, right?” I asked. He nodded. I explained that everyone from Pittsburgh gets that treatment — it’s a band in-joke that refers back to the late-’70s basketball comedy “The Fish That Saved Pittsburgh.” I’m not sure he was satisfied by the answer. The Fallon walkovers, as trivial as they may seem, have been the culmination of everything I’ve cared about my whole life: making strange musical connections, reveling in the way that something obscure can illuminate something obvious.

Because the songs we select are a kind of code, some of the guys in the band use them to slyly flirt with female guests. I let Kirk talk me into playing The Lonely Island’s “Lazy Sunday” for Christina Ricci because he had heard she has a “Chronicle of Narnia” tattoo on her back. I did it but got no reaction at all. I put him on six-month probation for that suggestion; he was forbidden to send any more secret messages to anyone. And I can remember one case where I totally fumbled the ball. We had a famous actress on — I won’t say who, to protect both myself and her — and I thought she had been in a particular movie, and I built the walk-on around that title. After the show, her publicist came up to me. “Hey,” she said, “what was the walkover song? I’m not sure I understood the reference.” I had confused her with someone else. I was so embarrassed.