will becomeInformal contraction of なってしまうの. It is used when something ends up becoming something, often with a sense that it happens naturally or unfortunately. In the examples, it follows a noun plus に, as in 狼になっちゃうの.
JA: この薬を飲むと、すぐ眠くなっちゃうの。
EN: When I take this medicine, I end up getting sleepy right away.