Gyarados Effect
The effect of someone or something getting infinitely better/more badass/awesome within a short space of time, similar to how a Magikarp can evolve from a horrifically weak pokemon into a Gyarados, which is very powerful.
Amanda: Hey, have you noticed how Neville in the Harry Potter films is now really hot?
Jill: Yup, it's the Gyarados Effect.
Jill: Yup, it's the Gyarados Effect.