Lyric discussion by ABookOnAShelf 

Cover art for Baboon lyrics by Mountain Goats, The

I have a tape of this song, from 2004 in SanFran. John introduces the song with:

"This is a song I sing, that I want you to have in your heart when the day comes that you see a person whose lips, when they first met yours, filled you with a joy that you had not known before that day. When the day comes that the same lips fill you with the revultion you would reserve for an open grave, I want you to know this song. You may not want to sing it, you may not want to remember it. But I have sadistic tendencies! And I want you to remember me on that day, cause I've ben right down there with you."

It gives it a good bit of context, I think.