Well, if you really want to know, it's a Wiki article about a one-hit wonder "band" called Steam, and their 1969 #1 hit song.
"Gary DeCarlo, Paul Leka and Dale Frashuer wrote the song in the early 1960s, when the three men were members of a Bridgeport, Connecticut band called The Chateaus. The Chateaus disbanded after several failed recordings. In 1969, DeCarlo recorded several singles at Mercury Records in New York with Paul Leka as producer. The singles impressed the company's executives, who wanted to issue all of them as A-side singles. In need of "inferior" B-side songs, Leka and DeCarlo resurrected an old song from their days as the Chateaus, "Kiss Him Goodbye" with their old bandmate, Dale Frashuer.
With DeCarlo as lead vocalist, the three musicians recorded the song in one recording session. Instead of using a full band, Leka spliced together a drum track from one of DeCarlo's four singles and played keyboards himself. "I said we should put a chorus to it (to make it longer)," Leka told Fred Bronson in The Billboard Book of Number One Hits. "I started writing while I was sitting at the piano going 'na, na, na, na, na, na, na, na'...Everything was 'na na' when you didn't have a lyric." Someone else added "hey hey." (Bronson,2003)
To everyone's great surprise, the powers-that-be at the label decided to release the song, now named "Na Na Hey Hey Kiss Him Goodbye", as the A-side on Fontana, a Mercury Records subsidiary. Leka thought it was "an embarrassing record, not that Gary sang it badly. But compared to his four songs, it was an insult." (Bronson, 2003) Since none of the musicians wanted credit for the tune, a nonexistent group, "Steam", was concocted. "Na Na Hey Hey Kiss Him Goodbye" rapidly rose to the top of the pop charts, topping the Billboard Hot 100 for a pair of weeks, on December 6 and 13 of 1969; it was Billboard (magazine)'s final multi-week #1 hit of the 1960s. A touring band, quickly assembled and dubbed "Steam" by their producer, Paul Leka, went on tour with the song but quickly disbanded in 1970."
I posted a short version in a thread that mentioned Steam in the title ("Steam is full of meanies!"), but it was totally irrelevant to the thread. But sometimes I just can't help myself!