'Foolish' in the Bible

And let there be no low behaviour, or foolish talk, or words said in sport, which are not right, but in place of them the giving of praise.

Do not be turned from the right way by foolish words; for because of these things the punishment of God comes on those who do not put themselves under him.

For this reason, then, do not be foolish, but be conscious of the Lord's pleasure.