If I confine it to transformer related, my most memorable was about 2 years ago now. My wife had been going on and on about how awesome the 'presents' were that she had for me. She was so confident and as it turns out it was the first, and last, time she bought transformers for me.

So as it turned out, I used to buy a lot of my bots from RK. She knew this and one day bought me all the bots that she thought I was interested in. She based this on the screen I left open at the time which happened to be the latest arrivals screen full of things like the transforming hats/shoes and some movie bots and other random ones that have nothing to do with my collection. She spent $500 on bots I had no interest in!

I couldn't help but laugh and thankfully she wasn't upset. Although I tried to put on a happy face and smile once I saw the list. Thankfully they were on pre-order and RK hadn't posted. They were good enough to give me a store credit and I ordered the ones I was after