For some reason ... for one of our keywords ... Google Contextual ads "impressions" skyrocketed few times a month. What is going on? Has any one experienced something like that?

If this is fraud, then what would be the point for them to do this if no one really clicked on the ads?

The only thing that happened is the Click Through rate for Google Contextual ads dropped significantly.

Anyone has anything to add here? Thank you.

Check your backlinks and the keyword in Google. How far are you in the rankings on the keyword?