The 50-year-old was left with her mouth on the floor quite literally after he dropped the oral sex innuendo during the news segment.
He made the crude remark after Kate said that a recent study revealed that smiling makes people look older and the best way to combat it was by looking surprised.
“A big grin makes us appear three-and-a-half-years older,” she explained to Ben and co-host Susanna Reid.
She continued: “Apparently, if you want to stay younger you have to adopt an expression of surprise and shock because that stretches out the facial lines.”
Ben asked: “How do you do that?” Kate then proceeded to open her mouth as wide as she could in a bid to adopt a shocked expression.
“Yes, I had a girlfriend like that,” Ben quipped in response as he started chuckling mischievously.
However, Susanna, 42, lifted the tone out of the gutter as she assured Kate: “But as we know, you look fabulous at 50.”
She was heard grilling about the party’s decimation at the local elections as she asked him bluntly: “Frankly people were asking: What exactly is the point of UKIP?”
The MEP, 40, hit back: “Well, we’re the only party going into this election with clear policies to cut foreign aid and re-invest that money into the national health service. We’re the only party going into this election with a clear equality agenda.
“We’re the only party going into this election with clear commitments, real commitments to cutting immigration. We want to see immigration reduced to zero net over the next five years because we have a population problem in this country.”
Good Morning Britain airs weekdays on ITV at 6am.
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