Wikisimpsons - The Simpsons Wiki
The Squishee (sometimes spelled Squishy or Squishie) is a frozen drink, supposedly unhealthy, sold at the Kwik-E-Mart.
 General Information
Squishees are reputed to be dangerous to health, allegedly containing no natural ingredients, not even pure water. They have been described as "a thick, gloopy, tooth-rotting mixture of crushed ice and syrup". One customer, Nelson Muntz, even once had an out-of-body experience from drinking a Squishee.
Squishee syrup comes in a variety of flavors (listed below). Consistent with the Squishee's general unhealthfulness, Squishee flavorings can cause hallucinations if ingested in sufficient quantities.
Apu once had the Squishee machine at the Kwik-E-Mart replaced with one for a similar drink called the "Smooshie", which came in flavors such as "shopping bag" and "dog fur". Apu made the change after he had a fling with the Squishee syrup delivery woman, and chose the Smooshie because its deliveryman was an ugly hobo and therefore wouldn't tempt Apu into being unfaithful to Manjula again. The Smooshie did not go over well with Apu's customers, however, and the Squishee quickly returned.
It is possible, but difficult, to make a Squishee entirely of syrup. The syrup level has to be adjusted from "Recommended Dosage" past "Unhealthy Dosage" to "Experimental", and there is a risk of damaging the machine in the process. Also, in an all-syrup form, the Squishee cannot be drunk through a straw and is decidedly hallucinogenic.
 Behind the Laughter