On further research, the 'oq' and 'pq' parameters aren't search strings that I specifically entered, but are somehow related. When I search on "pyrun.exe", it sets "oq" to "pyrun":

http://www.google.com/#hl=en&xhr=t&q=pyrun.exe&cp=5&pf=p&sclient=psy&biw=1267&bih=662&source=hp&aq=0&aqi=&aql=&oq=pyrun