yo did you see jessica she was hangin with her backup friend lena only while amanda went to the bathroom then she started talking to amanda again  what a bitch
a friend who you use as a backup while your real friend is absent or gone or away at the moment
"yo did you see jessica she was hangin with her backup friend lena only while amanda went to the bathroom then she started talking to amanda again  what a bitch" What is the definition of "backup friend"?