meaning - What's a yellow line running down somebody's back

The only line between good and evil is the yellow one running down your back. What line does it speak of? I'm also not sure what meaning does "run down" have in this context. The source of

From Mechanics to Meaning and Back Again: Exploring Techniques for, back in game meaning

Pião Mágico em madeira - Fábrika dos Sonhos - Ludolica, pião em ingles americano

From Mechanics to Meaning and Back Again: Exploring Techniques for, back in game meaning

Wabs Talk Institute of Spoken English - ( #Join: 9999947824, back in game meaning

Back in the Game (TV Series 2013–2014) - IMDb, back in game meaning

Panthers place McCaffrey on IR; RB can't return until Week 9 - The, back in game meaning

Meaning of Back in the Game by Battle Tapes, back in game meaning

Panthers place McCaffrey on IR; RB can't return until Week 9 - The, back in game meaning

Meaning of Back in the Game by Battle Tapes, back in game meaning

Pião Mágico em madeira - Fábrika dos Sonhos - Ludolica, pião em ingles americano

From Mechanics to Meaning and Back Again: Exploring Techniques for, back in game meaning

From Mechanics to Meaning and Back Again: Exploring Techniques for, back in game meaning

💌 on X: “Please end the game and start again” The meaning is, back in game meaning