[makeworld]

    cat /dev/urandom | aplay

Still works well on my machine, and I use it all the time to test :)

[umanwizard]

Ah, neat, but I seem to remember catting it to an actual device node, not to an executable.

[adamnew123456]

You're thinking of /dev/dsp, which was an OSS thing before the move to ALSA. It still exists on the BSDs AFAIR but has to be emulated on modern Linux: https://unix.stackexchange.com/questions/103746/why-wont-lin...

[umanwizard]

Yep, that’s the one!