If I could turn into Super Saiyan God, the first thing I would do would be basically mess around and play with it. I would because Deadpool (One of the coolest superheroes!!) says that with great power comes great irresponsibility.
The second thing I would do is fly to any other planets and correct other scientists and make them look dumb, and make me look AWESOME, which I already am. Maybe. I am probably. Okay, back to the topic.
The funnest thing would probably be chaos! Testing out superpowers on useless buildings (like school. Dude, there is something called internet, where you learn stuff, HELLO! You from the 1800’s?) and replace the “useless’ stuff with awesome stuff! Like theme parks, toys, spy stuff, colleges (like special ones, e.g. MIT, which is almost the only cool school on Earth) and a bunch of other stuff for kids. (What? Kids deserve more!) The entire Earth is gonna be much better with this.