Trump didn’t say it. A lady in the audience said it. And Trump publicly reprimanded her.
https://www.youtube.com/watch?v=JB259lgEorA
Apparently, she said it because someone alledgedly wimped out on the waterboarding question.
If you get a chance Jim listen to Rush’s show today where he explains what Trump did. It allowed Trump to say exactly what she said while blaming her. Rush said as a fellow entertainer he had used the practice before himself.