This may possibly be the most amazing control in the history of controls. Found by a friend on a hotel air conditioner.

There are clearly only two options, blow hard or blow harder. Otherwise, just stop.

Of course, the usual method for designing an air speed control is a range from Low to High, communicated either with words or a graphic spectrum, plus Off. Also, “more” is typically clockwise to the right and “less” is counter-clockwise to the left.

But this control shows the danger when you try to use colloquial English terms for interface controls. Great theory, but proceed with caution.