To be very much in love; be powerfully infatuated: They would say that mouse has got it for Joey but bad/ He warbled the old song, ''I got it bad and that ain't good''(1872+)
The Dictionary of American Slang, Fourth Edition by Barbara Ann Kipfer, PhD. and Robert L. Chapman, Ph.D. Copyright (C) 2007 by HarperCollins Publishers. Cite This Source