Couching distance originally refers to the distance one can reach without leaving the couch or sofa. But now it can also refer to distance that literally requires you to leave the couch but is near enough anyway. 

“沙发距离”最初指无需离开沙发就能够到的距离。不过现在也可以指更远一些的需要离开沙发才能到达、但是也相当近的距离。

Example: 

That job is too far; it's not within couching distance.

那份工作的办公地点离家太远了，不在“沙发距离”之内。

I can't reach the remote control because it's not in couching distance.

我够不到遥控，因为它不在“沙发距离”之内。