Originally Posted by Peedtm

F'ing Smuckers makes it.

Or make your own:

Ingredients:
3 Pounds Red Plums
4 cups sugar

Directions:
Wash and pit 3 pounds of red plums, place in bowl of food processor and chop coarsley. Measure 5 cups plums. Add the sugar and allow to stand for one hour. Boil hard, uncovered until syrup sheets off a metal spoon, about 8 minutes. Remove from heat; skim off foam. Pour at once into hot sterilzed jars; seal. Makes 5 half pints.

Lifted from here