Understanding the history and "pen science" behind the ballpoint certainly helps to explain this. Nowadays ballpens are designed with many different types and functions like Retractable Plastic Ballpen, Twist Plastic Ballpen, etc.
http://www.cnluckstar.com/plastic-ballpen/twist-plastic-ballpen/
http://www.cnluckstar.com/plastic-ballpen/twist-plastic-ballpen/
Understanding the history and "pen science" behind the ballpoint certainly helps to explain this. Nowadays ballpens are designed with many different types and functions like Retractable Plastic Ballpen, Twist Plastic Ballpen, etc.
http://www.cnluckstar.com/plastic-ballpen/twist-plastic-ballpen/