I ain't happy, I'm feeling glad
I got sunshine, in a bag
I'm useless, but not for long
The future is coming on
A reference to Clint Eastwood film The Good, The Bad & The Ugly. Eastwood's character is asked whether he'll be alright, to which he replies:
Yeah kid, I got sunshine in a bag.
This refers to money.
This song is sung by bandmember Del the Funky Homosapien, who is conceptualised as a ghost, he is physically useless to others. However, he's doing okay because of all the money Gorillaz are making him.