。
Save some ice cream for me, will you?
Literal
I [to-に] ice-cream take-put [for-me-とい-て-よ].
とっといて is the colloquial contraction of 取っておいて — 取る ('take, hold') + ~ておく (do in advance) + ~て (request). The full form 取っておいてよ contracts in casual speech to とっといてよ. The meaning: 'hold/save it [for me, in advance].' The よ adds conversational emphasis.