I agree with @Spawn here. I think some Adware or installed browser extension got on your web browser of choice. I'd try to remove it from yourself. Then I'd go into your web browsing data and safely (stress safely) erase all web browsing data. Then, just to be sure I'd run ADWcleaner on your computer to ensure all is a'ok. I'd run some other on demand scanners too, because I wouldn't want anything on my system - I'm sure you do not want anything either.Either some Adware or an installed browser extension that compares shopping deals.
@TairikuOkami makes a good point too. Make sure to check that stuff out as things can get hidden in there.Check out allowed sites and remove those, you do not know.
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