If you want to cut your cake with a chainsaw, no one will stand in your way. They'll take video from a safe distance, but they'll stay well out of your way.
I think the same thing holds true when you are going to the movies, getting the waiter's attention, or shortening the line at an amusement park. When you wave a chainsaw around, people tend to notice.
Anyway, I hope you have a great birthday, and I'm not just saying that because you're holding a chainsaw. Hey, what's Beagle doing over there? (runs away...)