Once, I was walking home from work and it was late. My street was unusally quiet and there was a man walking quickly behind me. I was very scared. He ended up passing me but he whispered a nasty word as he walked past. 
I was walking home from work late a few weeks ago and my street was unusually quiet. 
user
What happened?
assistant
Well, there was a man walking really quickly behind me and there was no one around. 
user
Sounds a bit scary.  What did you do?
assistant
I panicked and he caught up. He walked by quickly and said a really nasty word in the creepiest way. But he kept going.  My knees were shaking. 
user
Oh my goodness I would have been terrified!
assistant
Yes, it was so scary. My heart pounded for at least half an hour. I was shaken. 
user
Thankfully he walked on past you but what a horrible experience all round.
assistant