1 definition by TheScouseAssassin
A person who just copies everything his/her “friend" does. You don't want to be stuck in a room with a person and his/her sideman very long.
Joseph: John and Steve were having a cuss fight, and after every cuss John made, that twat Declan would keep saying “innit".
Philip: That daft cunt is such a sideman.
Philip: That daft cunt is such a sideman.
by TheScouseAssassin June 9, 2013