Most people chuckle when I demo the alcohol calculator. They especially like the drunkenness slider to select how drunk your guest are expected to get. I make sure to give them the background that it was an idea that I started in college. The ballistic one is extremely simple, but that was my first ever Android app and I chose it for that reason (didn't do a regular calculator because there are sooo many of them out there already).

I might as well add the link. https://play.google.com/store/apps/details?id=com.blogspot.t...