1- Well, when I read the question, I thought about when I found out I was pregnant, but not because it was a "bad surprise", but because it was the most shocking thing in my life and I was very scared. At first I was very scared and it didn't feel like a pleasant surprise, but then you give it your best and you realize that it's the most wonderful thing.
2- Leaving the supermarket, walking towards your car and realizing that they have opened your car and taken out a newly purchased air conditioner.
3 - When I was younger I had a boyfriend who was unfaithful to me, it was definitely an unpleasant experience, I didn't take it well, I didn't know how to handle it because of my emotional immaturity at the time.