How would you say shake that ass as in shaking your ass to the music in french? Would secouez ce cul be adequate?
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:
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 !)
"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.)