To evaluate the expression \(-8.9g\) for \(g = -3\), we substitute \(-3\) into the expression:
\[ -8.9g = -8.9 \times (-3) \]
Now, calculate the multiplication:
\[ -8.9 \times -3 = 26.7 \]
Thus, the value of the expression is:
\[ \boxed{26.7} \]