意外的惊喜可以用英语表达为'pleasant surprise'。以下是一篇关于意外惊喜的英语文章：

Have you ever experienced a pleasant surprise? It's that feeling when something unexpected happens and it fills you with joy and happiness. Recently, I had such an experience and it left me feeling grateful and appreciative.

It was a typical Monday morning and I was on my way to work. As I rushed to catch the train, I noticed a lady struggling with her bags. Without thinking, I offered to help her. She gratefully accepted and we struck up a conversation. She told me that she was visiting from out of town to attend her granddaughter's graduation. She also mentioned that she was feeling a bit lost and overwhelmed in the big city.

As we approached our stop, I helped her with her bags and bid her farewell. Little did I know that this chance encounter would lead to a pleasant surprise. A few days later, I received a letter in the mail. It was from the lady I had helped on the train. She thanked me for my kindness and included a gift card to a local restaurant as a token of her appreciation.

I was stunned and touched by her gesture. It was a small act of kindness on my part, but it had made a big impact on her. Her gift was an unexpected and delightful surprise. It made me realize that sometimes, the smallest gestures can have the biggest impact.

In conclusion, a pleasant surprise is a wonderful thing. Whether it's a kind word from a stranger or an unexpected gift, it can brighten your day and lift your spirits. So keep your eyes open for those moments of unexpected joy, and be sure to spread some of your own.