Yep mixed marshmallow fluff, cool whip, frosting and some warm water to make super sticky slime and pie filling. ratio was 2 large tubs marshmallow fluff, 4 tubs cool whip 2 cans frosting and about 4 cups warm water.
How funny. Literally just did this today. Marshmallow fluff though. Not marshmallow cream. But I take two large tubs of cool whip, one large tub of fluff and then a standard cake frosting cup from pillsbury or something. The fluff and frosting make the whipped cream thicker and more spreadable but the fluff specifically makes it more ooey gooey and improves the texture. It's heavenly.