Best friend...by default
When someone tells you you're their best friend but you are painfully aware you're their ONLY friend.
Chum: "you're my best friend"
Lee: "yeah! Best friend...by default!!"
Lee: "yeah! Best friend...by default!!"
best friend by default
When one has only one friend and must rank them as their best friend due to the fact that there are no runners up.
Person 1: Hey man who is your best friend?
Person 2: Bob; he's my best friend by default.
Person 2: Bob; he's my best friend by default.