It may be cheesy, but whipping out an origami flower while you're at the dinner table can really make someone's day, whether it's made out of a napkin, dollar bill, or burger wrapper. It's great for showing your waitress how much you appreciate the service, or for breaking the ice with your Valentine's Day date.
I've used this little trick throughout my life, and most memorably, one time in Hawaii when my girlfriend (at the time) went out to lunch with me. She was actually very impressed, and now we're married with three kids and counting.
WARNING: Making paper roses for more than one person at a time may lead to jealousy, confusion, and/or competition for your attention. Use of video content is at own risk.
This was an amazing little trick I learned around 15 years ago from a good friend. We were at a restaurant one night, and he blew my mind by turning one of the napkins into a rose.
Since then, I've used the trick quite a bit, and played around with making the decorative hood around the flower head to get this awesome effect. I found it works with hamburger and taco wrappers as well, so you can turn a humble eating accessory into a clever expression of your affection.
If you don't have a special someone, try using it as a fancy way to tip that cute server that just brought you your food.