Added to this is the fact that I am pretty (very, probably) easily amused and while my husband has an excellent sense of humor (which I just love), he often does not find humor in the same things I do.
So...my big plan was to go to his work and decorate his car, which I did. It was a risk, because on the wrong kind of day, this could really irritate my husband. But, the more I thought about it, the more it cracked me up and I decided it was worth the risk. I was so conservative with it. I could have done so. much. more. I ended up just doing a couple balloons and some window paint (which was actually much harder to find than I thought that it would be). I wrote "It's my birthday!" backwards on the front window so that cars in front of him would be able to read it. I had to practice it at home and bring a piece of paper with it written down with me so that I would be able to write it under pressure, with no mistakes. I certainly didn't want to have to try and clean that stuff off of the window!
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My husband did end up texting me to let me know, that he knew, that I had been there. He went to go and get a drink on a different floor and saw the balloons on his car. He also saw the other decorations and told me that he was going to clean it off before he drove home. Oh well. That was probably a given. I still got a great laugh out of it (I told you I was easily amused!!).
Thanks Honey :)