What does “baratin” mean in French?

Le baratin is talk designed to work on you: a salesman’s patter, a chat-up line, an excuse dressed up at length. Arrête ton baratin is “cut the nonsense” — you are calling the words empty rather than calling the person a liar outright. It is informal but not vulgar, and it usually lands as weary rather than furious, which is what makes it so usable.

The verb is baratiner, to spin someone a line or to chat someone up, and un baratineur is someone who does it by habit — a smooth talker. The noun stays neutral enough that people apply it to their own excuses.