Just to add to what Saqib has said - 'Crikey!' is an exclamation which shows the speaker's surprise. "How much was that cup of coffee?" "Seven euros" "Crikey! I'm not going in that cafe again!' It's what's known as a 'minced oath' - an exclamation based on a word would have been seen as a profanity in the past. Rather than say 'Christ! , which might offend some people, we say 'Crikey!' or sometimes 'Crumbs!' to represent the stronger word. Here are some more minced oaths - heck, darn, gosh. What words do you think they replace?

It's used to show that you are surprised at something.- it's a very British expression. Some examples "Crikey, it's hot today!" or "It's so hot today.. Crikey!!". "Crikey, these sandwhiches are good!"