Editor Snap to floor?

Is there a hotkey like unreal to snap a gameobject in the scene to something below it like unreals end key? I know this somewhat partially exists because when you drag a prefab from the asset folder out into the viewport and continue to hold the mouse button down it will snap to what ever you are mousing over. But is there a key to do this when a object is already in the editor hierarchy?

I want it to work like it does when you drag a new asset out like this (but for existing assets in the editor). The vertex snapping is kind of too complex especially when its a high vertex model.

https://dl.dropboxusercontent.com/u/94084288/ShareX/2015/05/2015-05-29_00-47-54.mp4

try unity manual

Surface snapping

While dragging in the center using the Move tool, hold Shift and Control (Command on Mac) to quickly snap the GameObject to the intersection of any Collider.

There is ‘vertex snapping’ on the v-key when using the Translate or Rect tools.

Select the object you want to move.

Press V

Hover over the vertex you want to snap

Click and drag it to the vertex you want to move it to

Unity will move the object so the two vertices are touching.

(Edit: Who thought it was a good idea to have lines that are together merge?)