To touch on my favourite subject, the Franco-Manitobain-cum-Québecois singer Daniel Lavoie: there's a song of his called "Ça c'est ça" ([paroles][1]) that includes these lines:

> C'est rien que des mots quand même,
<br>sauf fais-toi-en pas.

I gather that this latter phrase is an informal version of "Ne t'en fais pas" and means "Don't worry about it" in Québecois French.

He pronounces it thus: [sofɛtwezɑ̃pɑ]

I recognize the [e] generally employed for the digraph "oi" in Québecois French, but the [z] caught me off guard.

My assumption: that it's something like the [epenthetic "t"][2] in phrases like "Sera-t-il ... ?" (perhaps an emulation of tenses that end in "t", such as "Serait-il ?", or perhaps truly spontaneous).

My questions would therefore be (and feel free to ignore this numbering):

1. Is that assumption correct?

2. Is the phenomenon limited to Québecois French? Is it still used? (The song is from 1977.)

3. Are there any other consonants that perform this role, or just [z]?

4. Has there been an analysis of the rules in which this [z] surfaces?