empty travel coffee mug on plane??

[luvchip]

Does anyone know if you can take your empty travel coffee mug in your carry-on?? I would like to take my mug with me on our trip and would use before we board the plane, but want to make sure once coffee is gone I can just throw in my carry-on bag?

 

[disneyldwjr]

Unless it is made out of gel or a prohibited item, there should be no problem.