Mommy took a bus trip and now she got her bust out
Everybody ride her, just like a bus route
A very lyrical way of telling an age-old story: girl came to the city and had no money (“bust out”) so she became a prostitute (or at least very promiscuous) who everybody “rides”.
Breasts are referred to as a “bust” because it comes from the name for a statue of the head and shoulders of somebody.
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