Definitions
1.NounA gift, purchase, etc. whose contents are concealed until after a selection is made; a bag as gift that comprises mystery prizes."Winners can choose a gift from the grab bags on the table."
2.NounA bag from which a gift or prize may be withdrawn (grabbed) unseen.
3.NounAny random assortment, selection or possibility."With that system, it's a grab bag which files we can find at any moment."
4.NounA moderately large bag of crisps or other snack, suitable for sharing.
5.NounA bag containing essential items, which can be easily picked up and taken in an emergency.