Some machines with a spiral mechanism to dispense had the occasional hangup. If you then chose that row you'd often get a double vend. It was disapointing if you didn't and you'd chosen something you were less keen in the expectation of a freebie ie you'd get the hung up item but yours would be the stuck one. Alternatively you'd choose an item above the hang up hoping it would collect the bonus item as it fell. These minor triumphs were far more satisfying than a free chocolate bar really merited
Yes - at work I always checked the machine for hang ups
and the best tactic of selecting next on that "shelf"
or the one above - or 2 above - and hoping it would knock one off
made my whole day when I got an extra item!!
My boss did once comment that I had fixed a major techy computery problem that was supposed to be impossible
but what made my day was getting and extra bar of chocolate!