"Thanks," Rick answers, ejecting the empty clip and replacing it with a full one. Handy thing about this place, he can just imagine up new ammunition. (How he managed to get that clip in with just one hand is a mystery.) Once it's loaded in, he turns to see who was talking to him - and promptly stumbles away from Karis. Since when could walkers talk?!
Wonderfully so!
"...the fuck are you?!"