How to drop things

So my 15 week old pup loves to chase and retrieve, but the problem is wehn she brings in the toy seh wants to then play tug. So I want to teach her to drop things. What is the best way to go about it? She is really a quick learner as she already knows sit, stay, laydown, dance, circles, and shake. So I don't think it will be too hard, but any ideas would be appreciated.

Thanks