PoC: I actually have a parody somewhere in my tapes of "Whiskey In The Jar" about a faithful golden retriever...
The one blooper I can remember came early in the a.m. at a filk convention. I was trying to sing Christine Lavin's "Ballad of Doris and Edwin: The Movie". In the original song, their meeting at the elevator is described as "His hands were full/she held the door for him/and he said thanks."
Due probably to the lack of sleep, I suffered pronoun trouble and sang "His hands were full/**HE** held the door for him/and he WHOOPS!" (as both the circle and I broke into laughter...).