He also told me that his mom was an illustrater working for "Frederick's of Hollywood". That's a lingerie brand like Victoria's secret nowadays. In the 50s and 60s she illustrated the catalogues.
Dave told me he was very popular with his friends, especially if they could sneak into the "atelier" to have a peek at the work at hand. I will believe these "dare-to-be-bare" drawings will jog a boys mind.