How can I stop people from talking my ear off?

DEAR ABBY: People are always collaring me, cornering me and then talking my ear off.
They drone on and on for long periods of time. Family does it, friends do it and so do strangers. It’s a social situation I dread. It gives me a feeling of claustrophobia.
Invariably, I can’t get a word in edgeways. It’s like people feel they have something to prove with me or are desperate for praise. I feel I can’t extricate myself without appearing downright rude or cruel.
This scenario happens SO often, I sometimes wonder if maybe something is tattooed across my forehead that encourages others to dominate me with their words. What can I do to stop people from chattering at me? — DAVID IN TEXAS