How you react to a surprise can vary if you liked the surprise or not. If you enjoyed the surprise, you can show how happy you are, say you were not expecting the surprise, and all around show your gratitude for the happy surprise. But, for the cases that you did not enjoy the surprise, the first thing that may come out of your mouth is a scared exclamation. After that, try and explain why you did not like the surprise, if possible. If the surprise was sudden and unexpected, express yourself as needed then try and take control over the situation so things don’t get worse.