soft as silk
Very soft, soft as a baby's bottomVery soft, soft as a baby's bottom
» Ask Mrs. Iguana how her back is, and she says it's softer than silk.
sabretou · Tatoeba · CC BY 2.0 FRDictionary text adapted from Wiktionary (Wiktionary contributors, CC BY-SA 4.0) and Open English WordNet / Princeton WordNet (CC BY 4.0, WordNet License); shared under CC BY-SA 4.0. Example sentences and recordings are credited where they appear.