To have an extra benefit or perk. My day off had jam on it once my doctor's appointment got canceled.See also: have, jam, on
have (or want) jam on it
have (or want) some additional pleasure, ease, or advantage.1974OliviaManningRain Forest Hugh…was free to leave at six…Pedley…said: ‘You've got jam on it: walking home in the sunset.’ See also: have, jam, on