Is a friend's jocular statement, "Without Wudu (ablution), and it will be fine," considered mockery of religion and forbidden, and is it necessary to correct him for that?

Joking with such words is a reprehensible act and is impermissible. It is not far from mocking the religion, and its least state is that it is a lie contradicting the saying of the Prophet, peace and blessings be upon him: "Allah does not accept the prayer of anyone of you if he passes wind until he performs ablution," and "Allah does not accept prayer without purification." This friend should be advised, for if he prayed without ablution or a legitimate substitute, his prayer is invalid and he has committed a grave sin.