A mixed CD of personal songs made by one person that he or she is too ashamed to share with his or her buddies. The most common type of confidential mix tape is a CD full of love songs for Valentine's day.

Noun: a friend who is usually only called upon by a friend when a more primary/prominent friend is unavailable.

Taken from the term “second string” in an athletic competition situation. In football, if the star quarterback gets injured during a play, the second string is called off the bench to replace him/her. A “Second String Friend” is essentially benched until needed, if ever.

Synonyms: Plan B, Second Choice, Secondary Friend, Benched Until Needed