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.