Eager and alert, as in Here is my new kindergarten class, all bright-eyed and bushy-tailed. The allusion here is to the appearance of a squirrel, which with its beady eyes and bushy tail looks ready for anything. [1930s]
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.