SOOKIE: This is about the time you start doing your little getaway dance. Two months right on the nose – you’re good.
LORELAI: I do not do a dance.
SOOKIE: You’re cha-cha-cha-ing right now.
The cha-cha-cha (or the cha-cha) is a Latin American dance which originated in Cuba in the 1950s. Sookie may be thinking of this dance in particular as it begins with the woman stepping backwards as the man walks forwards, just as Lorelai is backing away from Max.
The Annotated Gilmore Girls 