be very careful about what games you download from the google store!!!
i downloaded a bunch and suddenly i started getting this weird porn ad on my google search and my chrome browser started acting very weird. turns out a lot of apps can cause this. one of the main ones is super mario bros and super mario world (i had both of them).
I deleted all game apps except my solitaire one (because it seems pretty legit) and all the google brand apps and the kindle app.