sacudir el jibe: rock the cradle
como sacudia el jibe: the way (some)one rocks the cradle
Welcome to the forum!
In this context, it can't mean rock the cradle, as the whole sentence in the song is:
Cuando Juanita y Chan Chan /
en el mar cernían arena /
cómo sacudía el jibe... /
When Juanita and Chan Chan
were sieving sand by the shore
the way she shaked the sieve...
It refers to the sensual way in which she was moving, as right after the song says:
... a Chan Chan le daba pena..
wich roughly translates as: ...was driving Chan Chan mad