Lore Sjöberg: "here's what I often do: I put my laptop back into my satchel, put my iPod back into my coat and bring my entire life with me into the bathroom"
Lore ponders what to do if you're working in a cafe and have to use the bathroom. I think I would take option 4: pack it all up, emty my bladder, and unpack everything when I return. Fortnunately, when I'm in a cafe, doing some work, it usually is only for a short time so I actually never have this problem.
I don't use my iPod when working on my laptop, by the way: i just plug my earpods into the laptop and use iTunes or RealPlayer to listen to music.