it is a cantonese proverb, ponds only have water and fish, would not have anything else, which means the situation is always the same, i.e. family playing a mahjong game. the money balance is always the same in the end.
(slang) to go out to fool around (usually referring to a man who is playing around with other women behind his wife / girlfriend's back); (adjective) unreliable; slapdash; all show and no substance (to describe someone who just a snow job)