What is the origin of the idiom "ride the porcelain bus" and when to use it?

The origin of the idiom "ride the porcelain bus" is uncertain, but it is believed to have originated as a humorous and lighthearted slang expression. It is used to describe the act of vomiting into a toilet. The phrase is typically used in informal and casual contexts to add humor or make light of the unpleasant experience of vomiting. It can be used when discussing situations where someone feels nauseous or experiences an upset stomach that leads to vomiting.