Yes - misheard or missung lyrics are indeed Mondegreens, although I believe it was a lady columist in the Glasgow Herald who first used the 'Lady Mondegreen' line. Funny thing was my first ever posting to the Mudcat was asking if anyone had heard of a 'Mondelawn'. I had heard the term on the radio and mis-remembered! Hows about that then - a nested Mondegreen:-)Ronnie Barker was a master at portraying Prof. Spooner in the two Ronnies TV series.
But don't even mention 70's pop band Bucks Fizz....
Gnave the Dome