FYI: Your wang is not a water baloon:

Thailand's health ministry warned size-obsessed men on Friday to avoid trying to enlarge their penises with liquid injections, saying it could cause deformities.

The warning followed media reports that male teenagers in central Thailand had rushed to have their penises injected with olive oil or other liquids.

Maybe it's best there really is no way to enlarge it. Considering the popularity of pedestrian penis pills (ha!) and more extreme stunts like this, if there really were a way to enlarge it a significant percentage of the world's male population would be unable to leave the house.