adj. Mentally wacky, deranged, or cuckoo, maybe with a liberal tinge to match the conservative “moonbatty,” which is often accompanied by barking.
Real citation: "to give whiny, loonbatty, and otherwise obstructionist minded democrats a big head start digging up irrelevant but sound-bite worthy slime on potential appointment nominees"
(Wind Rider, June 24, 2005, http://silentrunning.tv/archives/006036.php)
Made-up citation: “Not all batty people are loonbatty, just as not all ratfuckers are rats.”