YOU KNOW HOW IT IS. You're scoping a familiar youth-orientated TV drama/comedy show and suddenly there they are: your favourite band! You spill your tea, fumble with the record button, and preserve all but the vital first 20 seconds for posterity.

Did you see that?! Stevie Wonder was on the Cosby Show! Yet why, exactly, is there something more thrilling about real rock'n'roll intruding into a fictional context than its scheduled appearance on a talk show or, god forbid, a dedicated music programme? Beats me.

In this blog, we celebrate those weird moments of juxtaposition - where rock and non-reality meet. We're not talking about unlikely pop stars fetching up as bit-part actors (like Iggy Pop in '90s Nickelodeon gem The Adventures Of Pete & Pete or Elvis Costello in Channel 4's '80s scousefest Scully or Phil Collins in Miami Vice). No, we're talking the "Troubadour Sequences" from cult US dramedy Gilmore Girls, where alt.rock legends like Sonic Youth, Sparks, Yo La Tengo, Joe Pernice and Grant Lee Phillips regularly featured as street buskers.

No matter how incongruous the setting, several decades of dedicated telly-watching has taught us that a game-changing pop star could be hiding around any corner. And if you're palling around with Bill Cosby, your odds just sky-rocketed: ol' Cos's enviable showbiz connections meant Dizzy Gillespie, Sammy Davis Jr., B.B. King, Lena Horne and Art Blakey all made guest appearances on The Cosby Show in the 1980s, with Stevie Wonder even inviting the fictional Huxtable family to jam with him in the studio.

The makers of hokey '80s comedy/action series The Dukes Of Hazzard, meanwhile, relied upon the illicit speed traps of corrupt Sheriff Rosco P. Coltrane to ensnare celebrity musical guests. Among those who sang at nearby tavern The Boar's Nest to avoid a night in the Hazzard County slammer were Tammy Wynette, Buck Owens and, in the clip below, The Big 'O' himself, Roy Orbison.

Set in the 1950s and centred around Rock'n'Roll-obsessed High School kids, long-running 1970s sitcom Happy Days seemed purpose-built for pop star cameos. Cue pint-sized sexpot Suzi Quatro, hoping to translate British glam rock success to home turf as distaff Fonz counterpart, Leather Tuscadero. Here she is, dropping a most anachronistic bass-solo in the middle of Johnny B. Goode...

Should any show boast a high quotient of teens in its cast and a venue-type location on the set, chances of a rock'n'roll cameo increase a thousandfold. This explains the bizarre occurrence of weird-rock wildniks The Flaming Lips turning up in Beverley Hills 90210 and playing She Don't Use Jelly for the rich kids at their plush hangout, The Peach Pit. "Well, they're not Michael Bolton," remarks a bemused Steve Sanders...