Okay, I saw it again, and it's some kind of cover of the song "Ain't We Got Fun" which I know Doris Day and some other artists sang. The lyrics are changed a little to something like this:
Every morning, every evening, ain't we got fun?
Not much money, oh but honey
Ain't we got fun?
Do as you like, dear, there's so much to choose
We've got it all here on our funship cruise
Wikipedia mentions that Carnival Cruise lines has used the song, but not who covered it:
http://en.wikipedia.org/wiki/Ain't_We_Got_Fun%3F
I hope this helped for anyone else who was looking for the song, but please let me know if anyone knows who covered it!