First we have the KINGSMEN classic Louie Louie. While later pondering the lunacy of the congressional hearings centered on whether the song's lyrics were obscene during the hit's heyday (hundreds of thousands of dollars wasted, but did a single politician think to simply ASK Richard Berry what the words were??!) one of the band's members noted that in the song you can actually hear the drummer blurt out "FUCK!" over a supposed mistake right before the second verse, around the 53 second mark or so (though, as with Hey Jude, the actual accident triggering the cursing is not really apparent.) That had not been noticed however, even as the entire country reeled over deciphering what the supposedly dirty lyrics were.
Next we have Hey Jude by the BEATLES. Preceding the repeated coda at just before the three minute mark John, again over an error that is not truly apparent, scowls out "fucking hell." It occurs right after the last "let her under your skin..." and in fact the immediate "OH!" that happens may be Lennon tripping up, and his grumbling coincides with the final lyric "then you begin..." Slightly less noticable than the Louie Louie's profanity (but impossible to ignore once you know about it!), the master recordings seem to bear out verification. Perhaps embarking on too many multiple takes of a song of such epic length seemed inconsiderable?
It would be rich to get the FCC's take on all of this...