Does anyone know how to kill a freshly laid egg?

Hello, my gecko recently laid her eggs. I don't want to sell or keep them, she's only about 4 months old and I don't want to incubate eggs for an additional 30-40 days. I've heard that putting them in the fridge kills the eggs, but how long does it take? Or is it even safe to keep them in the fridge? Any advice is appreciated.