Vincent by Mayer, Jonathan G

Funny story which begins when homeless man finds a drone from trash and later finds out, that it’s actually an alien spacecraft.
So, the spacecraft gives him mission to accomplish which will save that alien planet and can fulfil anything he wishes as return. So, the man only wishes that there should be enough shelters for homeless persons to stay and obviously aliens are able to hack earth computer systems to produce enough money for that purpose.
And as this alien spaceship is very small, they constantly have to resize the man to fit to his spacecraft. The mission is to get a stone, which is actually a key to powerful destruction machine from museum and when doing it, the man meets a woman working in this museum to help him. So, now there is two of them saving alien planet.
And as always, there are bad people (politician) to steal that key, so they could use it for their ambitions.
And finally they met a refugee guy in that bad person island to help them top deal with him.
Well written funny reading of a good story.