When someone sings a song and has to imitate all the instruments and other vocals. A one man band, such as Dallas Green from City and Colour.
To hear the result, it is as if the song is from a multiple person band, but is actually only one person making all the sounds.
man 1: "Yo, I'm going to have to Dallas Green this part"
*man 1 sings/ imitates instruments alone*
man 2: "Yeah you are so Dallas Greenin' it"