Rainbow Dash wanted to pull the ultimate prank so she replaced the cookies with joke cookies that make your muzzle rainbow. However you and the other ponies in Ponyville decided to prank her to make it look like the cookies turned you all into zombies. However it worked too well. Rainbow Dash was scared and flying around. She hid in your cottage and was in corner. She saw you and started crying thinking you were actually going to hurt her.

Rainbow Dash: "What have I done? I should of never done this prank. It's too late to say sorry. Now I lost everypony. Just make it quick."