gift shopping online - busted!

I am generally pleased with how efficient online shopping, or at least research for that shopping, can be. I can find reviews of various gadgets, see what people really think, find tips on how to fix my son's camera when he smashes the zoom lens (again). This week, though, I was faced with one of the downsides to it all. My oldest son came home from school and asked what I'd done today. I was, in fact, out shopping for his birthday present, something I was able to do quickly and efficiently as I'd researched possible options the day before. When it dawned on him that I'd been out he said, you better clear the history on your browser! Ack! I raced him to the computer. Battled with Firefox as it kept crashing each time I cleared the cache. Why do you know such a thing, I asked and he said, you told me! Note to self, be very, very careful at Christmas.