It’s not weird. Trump is the master of the double entendre. He does it often and knows what he is doing when he does it. It gets him free airtime while giving plausible deniability later. Actually, it’s a brilliant tactic that has worked well for him.
It's only a double entendre if he leaves it hanging. He specifically was referring to begging. Look up "Beg" or "begging" in google images. People are on their knees begging. That's the mental image that most of us conjure up when we hear beg and knees in the context that Trump used it.
But the problem is some idiot wrote a headline that left out that information and then more idiots on this thread jumped to the conclusion that he was talking about a blowjob and then those same idiots refuse to acknowledge they were snookered by a headline.