Jane's friend
a. A "friend" that Jane uses to pleasure herself.

b. A commonly used nickname that Jane, and women alike,
use for their vibrator.

c. A device that Jane uses when dick is not around.
"Jane's friend is always there when she needs it."

Sally: "What is Jane going to do while her boyfriend is out of town for a whole month?!"
Mary: "Oh don't worry, I'm sure Jane's friend will keep her company."

"Every Jane needs a friend and every dick is a friend of Jane's."