Can you cut your stretch marks with a knife so that new skin will form and the mark will no longer exist?

You probably could - but that would be a really silly idea. You'd just end up with a hideous scar that was worse than the stretch mark to begin with. Stretch marks begin as red marks across the skin, but after a few months/years they eventually turn skin colour. So you can hardly see them anyways! And plus, both men and women get them. So be patient, you'll be back to gorgeous in no time!