어서 넘어지다

fall over because of something

An "-아서/-어서" clause naming the cause, plus 넘어지다 "topple over". Every line supplies what made someone go down: hit the guardrail and fell, someone hit him and he went down, the cow was startled and had fallen over, the orca got pushed and went over, jumped over the bathtub and fell. One line uses it as a joke about food — it's so good I feel like I'm going to fall over. 넘어지다 is falling from standing; falling from a height is 떨어지다.