"Secouer" does not correspond to idiomatic French in that context. A verb that would belong to that context is "tortiller". However there is not really in French the counterpart of such statemments as addressed to someone viva voce. A somewhat modified form would do; here is one.

• Allez, tortille du/le/ton/ce cul (as spoken to somebody as an interjection)
• Allez, tortillez du/le/vos/ces cul (                             "                                 )

It is certainly not something common in French literature as it is not found in Google books. The expression is found in 1690 (TLFi).

• 1640 tortiller des fesses (Oudin Curiositez); 1690 tortiller du cul (Fur.)

Cul isn’t a good choice in that context, being too dismissive.

I’d suggest something like:

Allez, remue-toi !

Bouge ton corps !

Trémousse ton popotin ! (a little childish and/or jocular)

Secoue tes fesses ! (Thanks @LaurentS)

Younger generation might use boule for ass and say:

Bouge ton boule !

or even

Move ton boule !

I guess some people downvoted me for suggesting that !

(En complément de la réponse de Jlliagre)

Dans un contexte musical, pour danser, on peut aussi dire

Allez, on remue les fesses

Allez, on bouge les hanches

On utilise aussi l’expression

Se bouger le cul

Mais plutôt pour signifier qu’il faut se mettre en travail

(I y a une variante, mais que je préfère ne pas donner ici !)