"Uhhh--" She looks at him, looks at the knife, looks back at him and gives him a bemused smile.

"What, you're not going to let me cut my own cake on my birthday?" She says, instead of something more along the lines of 'R, you zombie, give me that knife'. She holds out her hand expectantly.

"Don't worry. I'll cut you a nice big piece. You can mash your whole face in it, if you want."