person(s) who are only acceptable to hang out with during the summer; or person(s) that only make sense to hang out with during the summer months due to vacationing proximity (ie., shore rental towns) when otherwise varying chosen professions, walks of life, circle of friends would render the friendship null and void.

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

In Internet forums and chat rooms, this phrase is used sarcastically as a response to a low-effort comment or bad attempt at trolling, to indicate to the author of said comment that his is immature, a newcomer adolescent as a result of excess free time stemming from summer school vacation. The meaning is closely related to a modern Eternal September.