You should resist the temptation of stocking up on mayo, even though your grocery store is having a killer sale, because freezing these extra jars will do no one any favors. When mayo thaws after being frozen, it will separate and take on a clumpy texture.
Leftover gravy is a very problematic thing to have in your kitchen. Although it tastes delicious, it’s only able to last at the very most two days in your fridge. To complicate matters, cream and milk-based gravies won’t hold up nicely in the freezer, as they’ll separate and turn lumpy when thawed.
Frosting that is egg white-based is not meant to be kept in the freezer, as it will lose its fluffiness and start to “weep”, also known as emitting liquid, once it thaws. The same should be applied to meringue, which is also derives from egg whites.