can't figure out how to win the water gun fight. i have chengs mix, just no idea when to put it in the gun
Wait, try to hit, as in you actually clic to do it? I don´t think that is ever an option. When you get to the twins it is just a cutscene where you run out of water and the twins shoot you. Are you sure you are at that part?
That dialog sounds more like what you get when you try to attack the blond and the dual wielding chick. In which case you should not shoot at them and instead take cover behind the tree.
(The gun should be at the shop right after the battle ends with the dialog about buying it. It´s under electronics.)
After Priti gets shot you come up against April and Alice. Take cover then and you'll end up sneaking around the side and encountering Cassandra. Get past her and then you come up against the twins. You'll always get shot the first time you fight the twins. After you get to them though a new water pistol will unlock in the online store (under electronics).