Google Chrome Popups?

I use Google Chrome to do my research, play games, etc. It started on the weekend, I noticed something odd about most sites I use and I want the readers here to understand carefully. I'm starting to see a lot of random words have two lines under them and when I hover my mouse over the random words, an ad shows up. Also, when I click on a link, a new tab automatically comes up and the new tab is a ad or some sort or a pop-up. I've never have a strong amount of ads or random words become ads. For example, on a site called "Newgrounds", I was playing a game. The description of the game had the word "Christmas". That word had two lines underneath it, the word was a different color and when I hovered the mouse over the word, it will show an ad. Normally it shouldn't do that. Does anyone know my problem or what I should do?