Two important metaphors

A dog with two bones:

A dog, carrying a bone in his mouth, passes over a stream. He sees another dog in the water, with a bigger bone than his. The dog decides to try and take the bigger bone, and he opens his mouth to grab it. His own bone falls into the stream and is washed away, and he comes up with only a mouthful of water.

Upsetting the apple-cart:

"to cause trouble, especially by spoiling someone's plans"(ref). To have somethign working just fine and then get rid of it and anger the people around you.

Now, can a dog, trying to get a bigger bone, knock over an apple-cart? Have to be a big dog...

And, because it seems a propos: