During a conversation that took place in Montréal, a woman said in French an equivalent of this: “Buy him some chocolate; he likes that.”
Here’s how she said it:
Achètes-y du chocolat ; y’aime ça.
Buy him some chocolate; he likes that.
Achètes-y? What the woman said is an informal equivalent of achète-lui du chocolat, il aime ça.
In achète-lui (buy him), she contracted the lui to ‘i (shown above as y).
But that’s not all:
In codified (standard) French, the s of the imperative achètes drops before lui, which is why it’s achète-lui, and not
achètes-lui. But when the contracted form of lui is used instead, the s is retained in colloquial language: achètes-y, and not achète-y. This means the contracted ‘i (or y) really sounds like zi (achète-zi).
achète-lui: codified French
achètes-y (achète-zi): colloquial French
In the second part of what she said, she contracted il to i’ (shown above again as y).
il aime: codified French
y’aime: colloquial French