Horse of a different color        
          : Different issues / stories

Horse around    
          : Play around

Hit the hay
          : Go to bed

Hit the road
          : Go to work / go out

Have a weakness of
          : Cannot resist on something usually negative

Heart and soul
          : Dedicate to something very much

Have an ear for
          : Good at listenning some instrument.

How come?
          : Why?

Hit the books
          : Go study

Here you go
          : It's for you

Have no clue
          : Have no idea about something

Holding grudge
          : Have unfriendly feeling