the.com/sweet talk

means To use flattering, charming language to persuade someone or coax them into doing something they might otherwise resist.

from A straightforward compound from 'sweet' (pleasant, flattering) plus 'talk,' first showing up in American English in the early 1900s. The metaphor leans on the old sense of 'sweet' as agreeable to the senses — the same instinct behind 'sweeten the deal' — treating flattery as sugar that makes a bitter request go down easy.