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!!"
by Chumbo82 July 17, 2017
Get the Best friend...by default mug.
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.
by Keael February 27, 2006
Get the best friend by default mug.