A few months ago I went to do a search from the Firefox search page (the default home page) on my computer and one of the previously run searches in the dropdown was for "pee porn." At the time it was a little upsetting as I thought maybe my temporary housemate was responsible, but the dates and times related to the search didn't add up. I looked through the history and could not find any evidence that anything was accessed after the search, nor could I find the search results page for this query in the browser history. Perhaps the history was deleted but I never figured it out, the computer eventually got reformatted and I didn't think about it again.
Fast forward to a few days ago, my daughter and I were playing a game on my wife's laptop when I alt-tabbed out to Firefox to look up something for the game. On the Firefox search page, in the first five entries was a search done for "girl eats own p***y". I shooed my daughter away and looked at what else was on the list; there was "huge c--t porn," "men lick their c-- off girl b------," and possibly others (you get the point).
Assuming these searches are related, this set of fetishes is so diverse and in language that neither of us would ever in a million years use that my first guess was that this is all some kind of SEO attempt. The thing that gets me though is that I can't find any evidence that these searches are ever completed or that anything is accessed as a result. I 10000000% don't believe it's my wife doing this, I didn't do it, and I don't have any kids or visitors who would have done it either.
Virus scans are clean; both affected computers run Adblock Plus and the laptop in question just came back reformatted from the shop in May.
Anybody else have anything like this pop up on home or work computers?
Thanks
edit: I'm starting to get some validation in that I'm not the only one who seems to have this problem. This google thread (http://productforums.google.com/forum/#!category-topic/websearch/unexpected-search-results/dmT4efq3-HY) has a bunch of people complaining about weird searches showing up in their Google History.