At first you think, maybe it's an emotional outburst from a young woman who is frightened of entrapment--perhaps a deep fear or romantic entanglement.
Yes. To be caught is to die. Profound--Even if it is written on a door. It's a poetry jamb. Or maybe a door slam.
But then, you think, no, it's more likely a veiled prediction. A promise. A passive-aggressive curse from a spotty teen directed at the object of his unrequited desire. He knows he can't say "I will kill her when I catch her" because if he does, and her father happens to see it, he might have his tiny arms torn off. The end of a promising graffiti career.
It's very much an Irish thing. The idea of justice delivered--by somebody else, a powerful entity, a Deus ex machina, as the chap with the Magic Marker might say, swooping down and smiting the faithless lover.
But why is the 'g' in 'caught' almost invisible? It's possible he wrote C-A-U... and then paused, tongue stuck out the side of his mouth. The ink drying on the felt tip. Was he thinking of Tom Wolf's quote about writer's block in the Paris Review?
"the fear you cannot do what you’ve announced... or else the fear that it isn’t worth doing."