Amazon actually seems to be where these are coming from. See Amazon's listings for "Blowjob" (a CD single by "Sober"), Marijuana (a book on subtance abuse by Sandra Lee Smith, link to main version), and Prostitute, a CD by Toyah.
Here's what I think is going on. The clue is the ASIN (Amazon Standard Identification Number) that's in all the Target URLs - you'll see the same number in the Amazon URLs. Each of these items has two main features - it has no identifying photograph, and it has a weird name. The Target site is much more minimal than the Amazon site, so it looks a lot weirder there, and a lot less obviously like a CD or book. Check out, for example, Target's entry for the standard edition of Marijuana. It's obviously a book about substance abuse.
Why does Amazon have these weird entries? In the case of Prostitution and "Blowjob," I think it's because they're so obscure. No further information has been placed about them. In the case of Marijuana, I suspect it's because a slightly corrupt entry happened. I'm guessing what's happening here is that people have discovered they can search for weird things and sometimes find them. But, it's just an artifact of the fact that Amazon backends Target's website for them, and Amazon's database of items is so huge that it both has weird items in it, and no one has seen all of those items.
April 2002 May 2002 June 2002 July 2002 August 2002 September 2002 October 2002 November 2002 December 2002 January 2003 February 2003 March 2003 April 2003 July 2003 September 2003 October 2003 November 2003 December 2003 January 2004 February 2004 March 2004 April 2004 May 2004 June 2004 July 2004 September 2004 October 2004 November 2004 December 2004 February 2005 March 2005 April 2005 July 2005 September 2005 June 2006 July 2006 August 2006 September 2006