I don't understand silly pacts like that. Even worse is how the ads pointed towards fertility things. After going through hell with supposedly pregnancy, I think I'm gonna wait for a while longer before trying again.
I think these girls may have been sheltered from 8 or something and believe babies are as simple as those dolls they used to play with. Even worse, likely some STIs are passing around from such "pact" being made, they may be sharing the same guy but who knows. Crazy people.