So I've no idea if this just happens to me. I suspect not! Well I'm sure it's not just me but I've never asked anyone.
So I have pierced ears but never wear earrings.
Anyway now and again I squeeze around the hole on each ear front and back!
My left ear at the back is the best for producing a solidish lump.that is the length and breadth of the hole.
Did it today and got a good one as I hadn't done it for ages.