There's a saying, when things happen for the first time, it is an accident; second time, it is carelessness; third time and so on and so forth, it is a plot..
This girl here tried to kill me by tripping me when I was about to go down the stairs.
Suspect A: Teh Pao
Or maybe she thinks it is fun to see the human tripped and fell off the stairs.
Whatever it is, that is one thing that I will need to pay serious attention to, 'cuz this is the forth time it happened already.