Necks.  - 

neck tattoo

neck tattoo 2

neck tattoo 3

source, Anja K, pNiamhsexton

Arms.  - 

arm tattoo 2

arm tattoo

arm tattoo 3

 Johanna Marteleur, drawmeafteryou, Marit (Sweden)

Necks.  - 

OLYMPUS DIGITAL CAMERA

neck tattoo 2

neck tattoo 3

unknown, Rihanna, Alicia (Lyon)

Arms.  - 

arm tattoo

arm tattoo 2

arm tattoo 3

Oana Befort, letswedivide, Jacqui H (Perth, Australia)

Backs.  - 

back tattoo

back tattoo 2

back tattoo 3

unknown, Shirley N (Copenhagen), Ira (Ukraine)