>>3809291Helmut is a man, and it's a professional nickname, not his real name.
He suffered a head injury while riding his bike as a child, and this left him severely mentally disabled. Doctors said he should've worn a helmet, which would've prevented his retardation. So, you take the word helmet and you say it in a way that a disabled man would, and you get Helmut.
It's a tragic story, but he managed to do well for himself, using his disability as a way to garner pity nudity from the models. A success story if there ever was one.