My iPhone 4S is installing apps out of nowhere?

I have recently bought an iPhone 4S. I rarely use the App Store, what I mostly do is surfing in the internet through Safari. I don't open too "virulent" sites, I just access Facebook, WolframAlpha and some gaming sites (like Zelda Informer, which in normal browsers has lots of ads).

But then, suddenly, some days ago, some weird apps that I've never heard of appeared out of nowhere. That time I just freaked out and deleted them (actually, they hadn't ended their downloads yet).

Ok, they disappeared. But then, some days later, I'm checking the second "page" of the home menu and I see some weird apps. They are "Drunk", "Cadê?" (means "where" in Portuguese, my first language as I'm from Brasil. It used to be the name a search engine millions of years ago but I don't know if it's the same thig), "Office Lite" (has MS Word and Excel logos in it), KS Office (no idea of what is it) and "Documents".

I didn't open them, but now, instead of just freaking out, I printscreened and them deleted them.

Now I want to know: has this ever happened to you? What did you do? What does this mean? Should I be worried?

Hmm… Do you have anyone else who has an Apple product who is living with you? There's a setting that downloads the same apps they get. Maybe thats the problem. Or maybe you are accidentally clicking on ads and downloading things. If you still have problems I would suggest you visit Apple's website and report your problem.http://www.apple.com/support/contact/