It's called many things like "Butterfly" or "Albatross" style. It used to be common in the US in southern states. I think it started when people tried to get more power from their old red inner tube rubber. It's a fun style to try if you have longer, very elastic bands.You guys see that shooting style where he stretches the bands almost arm to arm and goes way back? That is amazing. Instinct shots at its' best. Love it.