Earbags sounds like either (1) airbags for your ears or (2) a sexual act of indeterminate but undoubtedly disgusting nature required to get patched in with an outlaw motorcycle gang. In this case the truth is somewhat more pedestrian; we’re talking fleece covers for your ears.
I saw my buddy wearing a pair while cross-country skiing and I gave him a ration about how dorky they looked. Once I had milked the topic to my own childish satisfaction I realized that yes, frequently it was only my ears that were cold, but in the same situation a hat or even a headband might be overkill.
So I bought a pair and I confess I was wrong. They are actually quite clever and useful and cool people do indeed wear them, as I myself prove. They keep ears warm during cold weather aerobic activity like skiing. For getting patched in with the Mongols, not so much.