The Blue Grass Appliance is a counter-conditioning device that is particularly useful in the mixed dentition stage of development. A teflon roller is placed in the most superior aspect of the palate. When patients try to suck their thumbs, the roller prevents them from experiencing the satisfaction of suckling. Instead, their tongue spins the roller. More positive than a strict habit-control approach, this presents the roller as entertainment -- a new toy. Note: With all habit appliances, an opposing model and bite relationship are required.