Lyric discussion by zackrandal 

Cover art for Nub lyrics by Jesus Lizard, The

It's about a kid who sticks his arm out the window of a bus and gets it lopped off. Sometimes amputees have "ghost limbs" where they can feel the leg or arm itching or hurting even though it's not there anymore. That's what the song is about. If the digital book of the album can be trusted anyway.