No, that’s not a thing here. Your American was pulling stuff out of his keister.
Many Americans don’t learn to properly use a knife and fork because of the ubiquity of fast food - many of us never really have to.
Go to a part of the country that’s upper SES, everyone knows how to properly use a knife and fork.
I am European too, but I heard this from an American. A knife is a weapon. They try to quickly get it out of their hand, in order that everyone else is able to relax.