In rock club DJing, the "toilet track" is an established set staple – a song long enough to allow the DJ enough time to sprint to the loo and back. It's usually denoted by the appearance of the Stone Roses' I Am the Resurrection (8:13) for a quick dash to the urinal and Fools Gold (9:53) for a more lengthy seated engagement.
The smoking indie DJ has a new God – DFA. As if LCD Soundsystem's Losing My Edge doesn't give you eight minutes of precious smirting time, their remixes can see you through a cigarette break, toilet stop, bar visit and bouncer punch up, and still leave you with a few minutes to pretend you're mixing it yourself. I favour their 12-minute saunter through Dare by Gorillaz or, if I've really got to jog to Aberystwyth and back before the next track, their 13-minute go at Goldfrapp's Slide In. That one's so long, danceable and innocuous that you could put it on repeat for the full two hours and even Alison Goldfrapp herself would still pay you in full at the end.
At Edge Radio in Hobart, the computer could go for hours. One of my main non-on-air collie jobs was ripping songs onto the DB. They were then there for all dj's to use, and the software had all kinds of nifty functions, like no > 6 minute songs between 9am and 6pm, and no songs with swearing between 7am and 8pm. Plus, if the next show didn't turn up, you could either hit "random" or make up a playlist.
Radio announcers, especially those doing graveyard shifts, would be familiar with this concept too. This story reminds me of something I've been thinking about recently as I've done shifts on 3CR - how many DJs (radio or club) are now using mp3 players with programmable playlists, or alternatively, burning a cd of songs in order for each show? I heard Anthony Carew refer to making cds for his show, and know of someone else who takes a laptop. Also, a lot of stations now have a computer system, and songs are played from hard disc. Apparently these can be told to "play songs until I get back", for DJs needing a bio-break.