drivel on

To talk, usually excessively, about stupid or nonsensical things. What is Uncle Ned driveling on about now? I told you not to get him started on politics! A: "How was your date?" B: "Eh, not great. She just driveled on all night about the most inane things. I couldn't wait for it to be over." A: "I didn't know anyone could drivel on about envelopes and postage for that long." B: "Well, he does work in the mail room."