The line expands on his character's comment to his daughter in the musical Poppy (1923): "Let me give you just one bit of fatherly advice: Never give a sucker an even break." (This is the title of a subsequent Fields film, made in 1941.)
This quote from the musical "Poppy" (1923) – where it's said by the character to his daughter – is referenced again in a later Fields film titled "Never Give a Sucker an Even Break" (1941).