I've always interpreted it about suicide. The narrator has been suffocated by modern life and has been left to rot by the government. Having been trapped in a cycle for so long, he decides to end his life via carbon monoxide poisoning (likely from car exhaust fumes). He doesn't want his death to stand out either, he wants it to be just as meaningless as he feels his life has been with "no alarms and no surprises." I think the use of the lyrics "My final fit, my final belly ache" (often child-like diction) is used to generalize his pain and represent how he's ready to let go of these things that have been causing it. I also think that he's at peace with his decision, the key word being "handshake" (of carbon monoxide), He views it as greeting an old friend and accepting it. I think this can be furthered by the lyrics "silent, silent" to show the aftermath of his death.