Idioms of this kind are 'lexically filled', which means that they have fixed lexical items as part of their composition. For example, kick the mop does not have the same communicative impact as kick the bucket and spill the champagne does not have the same communicative impact as spill the beans.

Both kick the bucket and spill the beans are substantive idioms because most or all of the substantive or content expressions involved are intrinsic to the idiom.

Idiomatic expressions of this kind contrast with formal idioms.