Best get some recordings of Quebecois to see what's up.
 
Any tune that departs from the usual 4x32 form can be called "crooked". One of the ways that I have Quebecois musicians usually make a tune crooked is by playing the introductory notes of a tune in its own measure instead of grouping them in the last measure of the tune.  
 
Think of the Star Spangled Banner.  If you were to sing the first stanza over and over again, you'd sing it like:
LAN-AND OF the | FRE-EE AND the | HOME OF THE | BRAVE ___  OH-oh | SAY CAN YOU
A Quebecois musician would do this:
LAN-AND OF the | FRE-EE AND the | HOME OF THE | BRAVE ___  ___ | ___  ___  OH-oh } SAY CAN YOU

but they'd do it with jigs and reels.  I have worked with musicians that swear up and down they are playing straight tunes when they actually are not.  If you are unsure, it would be best if you can do a dry run with the musicians before the dance to alert them of your needs.  If the musician is flexible, they can do what you need.

Good luck!