Let's have Dirac mass term in lagrangian:
$$
L\_{M} = \bar{\Psi}\Psi
$$
Lagrangian must be real-valued, i.e., its Hermitian conjugation doesn't change it. But due to Grassmann nature of spinor fields, $[\psi\_{a}^{\*}, \psi\_{b}]\_{+} = 0$,
$$
L\_{M}^{\dagger} = -\bar{\Psi}\Psi
$$
Where I have made a mistake?