First of all, place the watermelon on a flat surface and use the cap of vodka bottle to make a circle on the surface of watermelon.
Now take a sharp knife and cut out the hole (made by vodka-bottle cap) on watermelon and separate the rind from it.
Make sure the hole is big enough to absorb the mouth of vodka bottle into it.
Now take a small spoon and dig out the hole as deep as possible. Use the spoon in a way to avoid destroying the shape of the whole.
Then you should hold the watermelon and insert the top of vodka bottle into it quite quickly.
Now place the vodka bottle upside down which means that the bottom of the bottle pointing towards the roof.
Keep it in a similar position until the vodka starts infusing with the watermelon.
After that, place it into the refrigerator in the same position. Make sure that the bottle is upwards from the bottom.
Now wait for almost 24 hours to let the liquor infused into the watermelon. Remove the bottle when it gets almost empty.
Then cut the vodka infused watermelon into slices and serve it. You can also freeze this vodka infused watermelon to make it an adult dish.