Place frozen meatballs in the crockpot with one jar of pasta sauce, mushrooms, black olives and water.
Allow to cook for about 1 hour or until all water has boiled out.
Once the meatballs are finished, place two meatballs (with a little sauce, mushrooms and black olives) into one egg roll wrapper and add the string cheese to the top.
Fold one corner toward the center of the egg roll wrapper.
Using your finger wet the other corner with a little bit of water and move it toward the center. It should come over the other side of the egg roll wrapper, and the water will help seal it.
Roll the bottom side of the egg roll wrapper up as tight as you can, wet the top of the wrapper and continue to roll the wrapper up. Check and make sure the wrapper is sealed everywhere.
If you find it's not completely sealed, add a little water to the unsealed places and press together.
Place meatball egg rolls in hot oil and cook on each side for 20 to 30 seconds, or until golden brown. They cook quickly, so keep an eye on them.
Remove from the oil and place on a plate lined with a paper towel to soak up any extra oil.