Our neighbors introduced us to "Slush" which we immediately renamed (with much affection) "Sludge." It's amazing.
-7up (pomegranate or cherry is best.)
I can't remember all my measurements, but I think I bought 5 cans each of pineapple and oranges, and just kept dumping them in until it looked like an even amount. I drained the oranges, not the pineapple. I used about half a banana because I think bananas are gross. So gross, in fact, that the second time I made it (with just one can each of pineapple and mandarin oranges) I left out the banana entirely.
So you dump all these in a freezeable container or a metal baking dish or something like that (depending on how much you want to make) and you mash it until it's mostly small chunks and juice. Then you freeze it. When it's time to consume, you cut it up into little chunks, put them in your glass, and drip some 7up over it. Mash it up with a spoon in your cup a little bit and it'll turn into a delicious slushie. You may need to keep your 7up with you so you can pour a little more in every few minutes. Don't make the mistake I first made, which was to put WAAAAY too much 7up in and so it was just like a fruited soft drink instead of a slushie. That was lame of me.