For my Idiom I was thinking 'cup of joe'. The idea just being a cup full of juice with the face being Joe. To make it a bit more interesting the steam could spell out the words of the idiom? Cup could be tea, orange juice, could add biscuits/saucer things like that? 

Another idea I had, I don't know if its a bit too complicated, an Orange with an arrow pointing to it saying Joe/This is joe or whatever, and then a cup of orange juice next to it with the idiom above. Not too sure, would love any feedback, thanks!