noun. An insanely nutty whackjob.
Related words: batshit loony, batshit whacko, batshit insane, batshit nutty, batshit nutso, super-batshit-insane, completely-fucking-batshit-insane, batshit-fucking-crazy, batshit-sounding, non-batshit, pre-batshit, anti-batshit, batshittery, holy batshit, batcrap, batpoop.
Real citation: "Oh, and when it was announced I was rather interested in the Obama/Keyes match-up. I had forgotten one point: Alan Keyes is a complete batshit loonball. "
(Frinklin, "RNC Day 4," Sept. 3, 2004, Frinklin Speaks, http://frinklinspeaks.mu.nu/archives/044157.php)
Made-up citation: "When a batshit loonball goes bugfuck crazy, all is not well."