[ConstantineXVI]

    cat /dev/random > /dev/dsp

Not necessarily the most pleasant sound. [Linux only AFAIK]

[philsnow]

For this exercise, /dev/urandom might be better; reading /dev/random will block after the system's entropy pool is exhausted, right?

[ConstantineXVI]

I'd consider it unlikely most reasonably sane people would actually want to pump random data out their speakers for any significant amount of time.