The randompoly command creates a random polynomial in the variables x having degrees in each variable up to d, and generating t terms with coefficients between -c and c.
randompoly([x,y,z],2,10,10000); 7820-6547*z^2+9026*x^2+6341*x*y*z+1607*x^2*y+4598*x*y*z^2-801*x^2*z^2-9405*x*y^2*z^2-2745*x^2*y^2*z+9696*x^2*y^2*z^2