Is the butt enhancing cream Curve safe and affective?

Waste of money. The only thing it helps is the wallet of the company that sells it.
Fraud. Can you imagine any topical cream changing the genetics and/or muscles and tissues deep inside the body? It does not happen. These kind of products, legal to be sold,, are not in any way going to provide any 'enhancement' to your body. Zero effectiveness.
Safe, but. The cream is safe "butt" it is not effective. It is a waste of your hard earned money and will not enhance anything but the sellers bank account.