neckdown
Someone who is useful, but only from the neck down; i.e. not someone to use for tasks that may require the ability to think or reason.
"Hey, Mike, can you get me a couple of neckdowns for that installation?"
neckdowner
A female that only looks good from the neck down. simliar the the term butterface
That hoe has a nasty ass face, but at least she's a neckdowner