(nuptial) winecups
卺 refers to a specific type of winecup used in traditional nuptial ceremonies, often a gourd split into two cups joined by a string. Its meaning is narrowly tied to this ritual object.
卺 is a specialized character for a ritual winecup. Its structure likely combines 丞 (which may have contributed sound) with 㔾 (a kneeling person or seal), but the exact historical development is uncertain.
The top 丞 looks like a pair of hands holding something, and the bottom 㔾 resembles a kneeling person. Imagine a kneeling person receiving a ritual winecup from above during a wedding ceremony.
For キン, picture a king (キン) and queen toasting with nuptial winecups at their wedding: king -> キン.