okay. I've been trying to think on this one.

Chan: back tattoo!! let him have another reason to show it off.
Minho: hear me out, hand tattoos. something delicate and pretty.
Changbin: bicep so he can flex and show it off.
Hyunjin: wow tramp stamp, you're so correct.
Jisung: I think the next one should be on his upper back as well.
Felix: V line tattoo!!! just below the belly!!!
Seungmin: maybe the inner wrist? something cliche and cute and about music so he can look at it.
Jeongin: NECK.