Don't Underestimate The Shy

Everyone's favourite (but not really) shy macro pony also has a mean side... a really mean side. Somepony REALLY annoyed her and now she's lost her senses. Way to go, pony. Whoever that guy was. Your house is getting destroyed and you're probably next. Don't try calming her. I doubt she'll return to normal until she does something bad to the other guy.
I'm just doing this as another side of Shift's personality. This rarely ever happens as she's usually a calm, quiet pony. In the case that this happens, she'll lose her senses and proceed to make herself huge in order to take revenge on... whoever pissed her off. Also, she doesn't really have sharp teeth. I just put it there because... just 'cause.
[EDIT]
She will also feel bad of what she did once she regains her senses.