potato bonus
Refers to the tasty spud-chunks that are included in canned mixed vegetables, as opposed to frozen bags of them that only contain the "standard five" garden-delights (peas, green beans, carrots, corn, and green lima beans).
Canned mixed vegetables are indeed blessed with a potato bonus, are pre-cooked and ready-to-eat, and do not require refrigeration till opened, but there are drawbacks to them when compared to just the frozen kind: they may cost more per ounce (i.e., over a buck for a 15-ounce can as opposed to maybe two bucks for a two-pound cello-bag; there is considerably less than the stated weight of solid veggies in the can, also, since a lot of the product's volume is made up of the broth that they're cooked in), they are often excessively salty, and they aren't usually so robust-flavored as the freshly-cooked fare you'd get from stewing up a frozen bag of them yourself, either.