My mother always used margarine and other containers for leftovers (yes... I never knew)
There was a time that she did home cake decorating lessons (and was very good at it) She would mix frosting (no color) earlier in the day and I would sneak in and stick my finger in and steal a big blob. One day she outsmarted me... just plain Crisco. I fell for it... gaged and I could hear her down the hallway laughing... never stuck my finger in the frosting again!