The story
From the notion that a person’s dedicated or loyal friend would stand their ground to protect them rather than walking or running away and would therefore keep all ten toes on the ground. Seemingly coined by the rap duo 8Ball & MJG in 2010 and popularised by the rapper Kodak Black, who raps the phrase in two tracks on his 2014 album Heart of the Projects.
Etymology from Wiktionary, CC BY-SA 4.0.