Rattle on
Definition 1 of 1
Pro Tip 1/3Negative Tone
Usually implies that the speaker is annoyed by the long, tedious talk. 
He started to rattle on about his collection of stamps, and I couldn’t hide my boredom.
Pro Tip 2/3Colloquial Use
'Rattle on' is casual and might be inappropriate in formal writing or speeches. 
At the family reunion, my uncle began to rattle on about politics.
Pro Tip 3/3Attention Span
The phrase suggests the listener may not be fully attentive or interested. 
During the meeting, I struggled to focus as she rattled on about the new policy.