It means talking incessantly and or to anyone and anything, e.g.
girls/guysbwho
don't reply, celebrities (via social media) who
don't even know if your existence.
o
"That guy
never stops talking. He could bark up a
tree."
Original coinage:
*replies to 5 story posts with paragraphs, receives only an emoji reaction*
"I could bark up a
tree *country accent*"