It may have been an after school movie? There was one student that was a hemophiliac, and they were all travelling to NYC together. It seemed like maybe late 70's movie based on the hairstyles. Of course on the bus ride one student pulls out the guitar and starts with the, "going to the big apple, gonna get myself a bite, going to the big apple gonna get myself a bite, CHOMP!". I have searched IMDB, google, yahoo, etc. I am counting on someone having seen this cheese flick, as web jamming has left me with nothing. I saw it on a UHF channel sometime in the early 90's, but my brother and sister as well as myself will always remember the catchy and cheesy song. I know this is a shot in the dark, but thought I could leverage the online community.
"Senior Trip"
http://imdb.com/title/tt0083051/