"Virevolte la grassouillette"

Our friend Marco, as any good French self-respecting, do not understand our french.
He buy a dictionary Franco-Québécois, "Parlez-vous Québécois?".
In this dictionary "Swing la bacaisse" is translated by "Virevolte la grassouillette".
When Lise has learned that translation she tears of laughter.
The proof is made, the best dictionary or the best translation software can not make sense to some expression.
ps: Welcome to my friend Marco, the owner of the famous dictionary, with us on Blip