there also is horse aroundMONKEY BUSINESS
from:http://www.wayland.k12.ma.us/loker/scho ... dioms.html
This idiom means to be silly or to fool around. This expression was comes from the 20th century and also comes from an old expression called "Monkeyshines" which dates to the 1820s. This idiom could be used if two kids were doing math problems and one kid leaned over and started wrestling with the other kid. The teacher might come along and say, "Stop that monkey business."
frog in my throat
sick as a dog
in the dog house