A thing little children that are afraid of doing actual graffiti do. Usually made from a glue stick a sock and a sponge, people are filling “water mops” with water and calling that graffiti. Copy a popular tag, put some water on a wall in your back yard because you don’t want anybody seeing you’re doing whatever the hell this is, wait for it to dry in 2 minutes and that’s that.
Friend 1: Did you hear that David got into water graffiti a couple days ago?
Friend 2: Isn’t water graffiti that thing where you write a tag with water?
Friend 1: Yes. Yes it is.