Three Cats Back Share definition Flag A Macintosh user who is still using Mac OS X "Panther", in spite of their being two newer versions (Tiger, Leopard) Pal: Hey, you load up Leopard on your machine yet? Me: Nope...I'm Mr. Three Cats Back! Three Cats Back by BWB January 5, 2009 0 0 Get merch Get the Three Cats Back mug. Buy Now — $32.95 See more merch