5301991f_and_The_Art_of_Breaking_Things__detailed_explanation
[signal] Thumb-sucking [part of body] mouth [possible meaning(s)] self-comforting [detailed explanation] 
A self-comforting impulse in babies and children, substituting breast-feeding, which can persist as a habit into adulthood.
“I pretty much try to stay in a constant state of confusion just because of the expression it leaves on my face.” – Johnny Depp | Zen and The Art of Breaking Things
detailed explanation