I don't know if I do it but my bf does it all the time and it is annoying so I shake him, shout his name to get his attention.
My pesky neighbor did this too and he had ADHD and I had to hit him to get his attention.
My dad does it too with sports and you have to bark his name. My mother does it when she reads and she gets mad when I shout at her.
I know lot of people do it when they are concentrating hard.