It Came from the Sky by Chelsea Sedoti

He was going to do a small explosion and see if his equipment he created would read it.  He didn't anticipate his brother adding more fuel.  It was no small explosion, it was huge! 

Sourcebooks Fire and Net Galley let me read this book for review (thank you).  It will be published August 1st.

At first the brothers created a story that a meteorite hit.  Then the older brother got inventive and said he'd seen aliens.  It took no time at all for that story to spread and for more people to say they had encounters with them, too.  Soon the small town was inundated with tourists.

Then the head of a franchise came to town.  He claimed to have been visited by the aliens and had a new product they told him to make that would make people live forever.  The brothers knew it was not true, but how to stop him?

Then there was the cow one of the brothers stole that got away.  This book is filled with silly things and young love.

As for the ending, the truth will come out.  The fake franchise will end, the boys will be doing community service for a while, and life will go back normal.  For a while anyway...