1 sm. can limeade
1 sm. can lemonade
1 qt. 7-Up
1 pt. rum
4 cans water

Pour all ingredients into large bowl. Mix thoroughly, cover, and put in freezer at least 8 hours before serving. Can be made up the evening before. Has a slush consistency.

I usually double this by using:

2 sm. cans limeade
1 lg. can lemonade
1 (2 liter) 7-Up (can use diet or Slice or any lemon-lime soda pop)
1 fifth bottle of rum (I use the most inexpensive brand and it works just fine)
4 lg. cans (lemonade can) of water

Be sure to use a big enough container because this will expand a little in the freezer as it freezes.