Used to be called a rodeo 5 back in the day of Szocs and Auclair. Some people might call it a flat 5, though those, when people first started doing them, were different. As for the Underflip, it is a little bit different rotation. It's almost like a 180 to Front flip, or a cross between a back 180 and lincoln 180. Now people have mixed up trick names so much, you'll get a lot of answers. If I saw it, I'd probably call it a back 180, or maybe a rodeo if it was a bit off axis. Mostly though, I probably wouldn't care what it was called and just be stoked people were killing it...