good song for ESL class?

i am teaching in a high school in China and it is geting near the end
of the year, I want to prepar my last class and make it fun and
relaxed, I thought a song would be a good idea, but I don't want to
give in the lady gaga/justin bieber stuff that would certainly please
my crowd but would damage my soul... I would like something not too
hard and with a goodbye theme maybe, or just outright fun...

so fun song, lively, not too hard but not too easy...

I taught "I feel good" at the begining of the year, that was a blast
but obviously can't do it again, but the level was perfect and there
was some shouting, and the kids had no idea who James brown was...

thank you Yahoo answer community!..