Hey Islandear -- I'm not sure if the Fugs did "Ballin in the Bathroom" first. Could be....the Fugs and David Peel (along with Zappa) were all loosely categorized together in the late 60s as rebel rockers.
But I remember distinctly the David Peel album with "Up Against the Wall Mother F---r", "Ballin' in the Bathroom", "Mother, Where is my Father?", etc.
I think that was recorded in about 1968, so if the Fugs did it before that, then they were first. I just know that we made copies of the Peel album on cassette tapes and passed them around in high school in the early 70s. Boy, that was a while ago.....