fish for something - to try to get information from someone.

a woman needs a man like a fish needs a bicycle(slogan) - a feminist slogan, suggesting that men are superfluous to women's needs.

teach fish to swim(proverb)- tell someone something which he/she has already known.

beat a dead horse - to continue fighting a battle that has been won.

horse trade - to bargain in a hard and skillful way.

as weak as a kitten - weak, sickly.

a fraidy-cat - someone who is easily frightened.

in a pig's eye - unlikely.

make an ass of yourself - if you behave so stupidly that you appear ridiculous, you make an ass of yourself. 

bee's knees - to say that someone/something is the bee's knees means that you think they are exceptionally good.

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