See in Scientific American:

“I could not survive without a ballpoint pen in my back pocket. It’s invaluable for scribbling notes on the front of my hand (my version of the PalmPilot…) to remind me to do things I used to be able to remember unaided before my age converged with my IQ while traveling in opposite directions.”

_John P. Moore

Professor of Microbiology and Immunology

Weill Medical College of Cornell University, New York City_