“Dat is niet zo!” is a quote from a rather obscure and unsuccesful Dutch movie (“De Orionnevel“). The only thing I remember about the whole thing is a fat man, with a beard, sitting on a chair in the street, who every now and then exclaims loudly: “Dat is niet zo!” (“That is not true!”).
Matxil comes from trying to write my name (Machiel) in such a way that Spanish or English people will pronounce it correctly. In fact, this is not the real way my name is pronounced, because the “ch” should sound like a hard gutteral “g”, but let´s not complicate things. In fact, Matxil was invented by a Basque girl whom I met 20 years ago, who ended up writing it like this.