It is possible to make friends with Debby Ryan, although whether or not she'd let you rub her feet depends on how good a friend you turn out to be to her. Debby Ryan, like most people, would probably feel awkward having a casual friend rub her feet.
A Favor to a Friend - 1919 was released on: USA: 18 August 1919
Although there were periods when massage fell out of favor, in the 1960s it made a comeback in a different way as a tool for relaxation, communication, and alternative healing.
Studio One - 1948 A Favor for a Friend - 6.19 was released on: USA: 25 January 1954
If you consider him/her a friend and they must be if you slept with them, it's common place to do a friend a favor-it doesn't mean you have to be more than friends.
The Whistler - 1954 Favor for a Friend - 1.21 was released on: USA: 10 February 1955 Japan: 23 March 1957
To act as a friend to; to favor; to aid, benefit, or countenance.
He was very thankful for the favour that his friend had done for him.
Mannix - 1967 A Small Favor for an Old Friend 8-7 was released on: USA: 10 November 1974
The Whistler - 1954 Favor for a Friend 1-21 was released on: USA: 10 February 1955 Japan: 23 March 1957
Ask a friend you trust if they will do you that favor. Though, it looks a lot better if you ask her out yourself.
A judgment in your favor is not likely since you made the arrangement in the deed of your own free will. The courts do not rectify errors of judgment.
Ask your friend directly for this favor, being your friend she will probably be happy to help (as long as you are just her friend and not in a relationship with her).