Good link Mr Happy:

In 1961, a group of music publishers representing songwriters such as Irving Berlin, Richard Rodgers and Cole Porter filed a $25 million lawsuit against Mad for copyright infringement following "Sing Along With Mad," a collection of parody lyrics "sung to the tune of" many popular songs. The publishing group hoped to establish a legal precedent that only a song's composers retained the right to parody that song. The U.S. District Court ruled largely in favor of Mad in 1963, affirming its right to print 23 of the 25 song parodies under dispute. An exception was found in the cases of two parodies, "Always" (sung to the tune of "Always") and "There's No Business Like No Business" (sung to the tune of "There's No Business Like Show Business"). Relying on the same verbal hooks ("always" and "business"), these were found to be overly similar to the originals. The music publishers appealed the ruling, but the U.S. Court of Appeals not only upheld the pro-Mad decision in regard to the 23 songs, it stripped the publishers of their limited victory regarding the remaining two songs. The publishers again appealed, but the Supreme Court refused to hear it, thus allowing the decision to stand.[13][21]

This precedent-setting case established the rights of parodists and satirists to mimic the meter of popular songs. However, the "Sing Along With Mad" songbook was not the magazine's first venture into musical parody. In 1960, Mad had published "My Fair Ad-Man," a full advertising-based spoof of the hit Broadway musical "My Fair Lady." In 1959, "If Gilbert & Sullivan wrote Dick Tracy" was one of the speculative pairings in "If Famous Authors Wrote the Comics".


Very interesting! Those are the ones I remember.
And this bit could have been a problem for many of us:

"The publishing group hoped to establish a legal precedent that only a song's composers retained the right to parody that song."

Robyn