Haha! Fooled me too!
I played a similar trick, only crueller, on the bf a while ago. I went to a lecture about angora wool and spinning etc, and met this beautiful white angora rabbit, Victor. I fell in love of course and talked about him for days. Then I went with my mother to a charity shop and lo and behold, there was a white angora rabbit:

I bought him and took him home and that night when my boyfriend came home, I shoosh-ed him and told him to be quiet, because of the little one that was sleeping on Bam’s bunk bed.
The look on my bf’s face when he saw this fuzzy white creature was not the look of a happy new owner of a huge white angora rabbit, I can tell you that. But then I hopped over to the “sleeping bun” and…

Revealed the true nature of our new “pet”!
I did feel really cruel for pulling a prank like that because my bf really beleived it for a few seconds – it was rather dark in the room and I had been talking a lot about the wonderfulness of angora rabbits. Still it was way too good a joke to NOT make. (And bf totally agreed, afterwards).