That is by far the friendliest graffiti that has ever been laid down. That's what Mr. Rogers would encourage you to write if he found you in an alley holding a spray can. What's the worst that could come of simply noting that you exist, that you're happy, and that you love your friends -- all in erasable marker, no less?
She was dragged out of class and straight to the police station, where she was put into an enclosed room and reportedly terror-puked during her interrogation. Alexa was then suspended from school and sentenced to eight hours of community service, where she presumably cleaned slightly less-friendly proclamations of love off of the side of a bowling alley.
Nothing discourages graffiti like eight hours of looking at kickass, colorful street art.