Lyric discussion by subsonic 

Cover art for Ticklish lyrics by At the Drive-In

"i only colored outside the lines 'cause i got the knack stenciled teen initials that were carved on the roof of my mouth"

i thought that line is sort of sarcastic, meaning because he experienced so many bad things, lost so many friends, he's kinda used to it, so he "colors outside the lines", meaning the chalk outlines on the floor around the body when someone died... sort of ironic/tragic/sarcastic...

then "stenciled teen initials that were carved on the roof of my mouth"

for example the 2 girls that died in a car accident at the age of 17, napoleon solo is about them, so maybe he cant stop writing/singing about them, like their initials were carved on the roof of his mouth... the stencil initials might also refer to some police-document or something dealing with the accident, on which their initials are stamped ...