The phrase "shoo-in" which means to be a sure winner, comes
from horse racing lingo. When corrupt jockeys conspire and
agree to hold back and to "shoo in," or urge forward, a slow
horse on which they have bet. In such a phony contest, the
shoo-in is the winner of a rigged race. In turn that seems
to have come from the verb shoo, meaning to drive a person or
an animal in a given direction by making noises or gestures,
which in turn comes from the noise people often make when
they do it.
from horse racing lingo. When corrupt jockeys conspire and
agree to hold back and to "shoo in," or urge forward, a slow
horse on which they have bet. In such a phony contest, the
shoo-in is the winner of a rigged race. In turn that seems
to have come from the verb shoo, meaning to drive a person or
an animal in a given direction by making noises or gestures,
which in turn comes from the noise people often make when
they do it.