The Cherry limeade slush is a drink offered at the Sonic drive-in chain across the US. The slush, available in small, medium, large, and Route 44 sizes is a near-perfect blend of tastes. The base flavor is, of course, lime. Both the lime and cherry flavors are added to the slush matrix by means of syrup concentrates. Sonic also adds small chunks of lime and cherry to the drink - a nice touch except when you suck higly tart lime fragments up through the straw.
The slush itself is a slurry of sweetened non-carbonated water and small ice grains from 1-3 millimeters in size. This, in my opinion, is perfect. I still rue the day that the 7-11 convenience stores switched from the slush base in their slurpees to the foamed fine-grained base they now use. Letting a slurpee sit and melt results in a cup about 2/3 full, while the volume of the Sonic slushes changes very little. Sonic has stuck to the traditional slush consistency, and as a result, the slushes they serve are substantial and satisfying.
The other quality of the slushes is that the temperature is, due to the high dissolved sugar content in the liquid, actually well below freezing. This can result in some really horrendous brain-freezes. This phenomenon usually ocurrs after the first couple of sips, and is an excellent reason to STAY PARKED until it is over. The discomfort lasts for five to ten seconds, is akin to a migraine, and is worth suffering to experience the slush. The brain-freezes also seem to be tailing off over time, such that I only experience them when I've missed my fix for several days.
My only gripe (not with the slush itself) is that they now charge the extra dime for an "added flavor" even though cherry limeade is one of the listed flavors on their menu (They also charge thirty cents for extra cheese - one slice!) If you get a chance, experience the sweet goodness of the cherry limeade slush for yourself. The blend of sweet and tart, if done at a competent franchise, will hook you forever. Get ready for a great brain freeze!