Chucking a water bomb and winding someone, technically counts as assault. Assault is an offense. Throwing a waterbomb in a water fight between consenting individuals is one thing, to target juniors and members of the public is an entirely different thing. How would you like to be walking along in the street, and then all of a sudden, being completely drenched, with your mobile and your Ipod in your pocket, so that they are so fucked up that they don't work anymore?
Pretty much, at my school, some Yr 12s glad wrapped some junior kids to a pole. Even though the junior kids were enjoying it, some people involved were suspended and missed our Yr 12 farewell - not because it was bullying - it wasn't, the kids were enjoying it and laughing - but because it was setting a horrible example to other junior kids. The Yr 12s involved were Prefects, and they were rightly suspended. Now that's nothing compared to a waterbomb on a member of the public (as in Kwayera's case). It was glad wrap, which is fairly easy to get out of, as opposed to a waterbomb which leaves you wet and can cause significant damage to electronics...
So yeah, in short, suck shit.