Analogue-sequencer

Hey gang,

one to think about here, if you're in the mood.
This evening I was working on a pattern in which I wanted three notes to 
play randomly. But (and here's the catch) I wanted them to either all 
play or none of them.

There are usually several ways to achieve the same result and I'm sure 
some of you out there would have solved it differently. So my question, 
before I post the tip, is: how would you have done it?

Paul