I figured knakworst(dutch spelling, how I know them) refers to that you can 'knak' them.
knakken is a dutch verb, I don't really know an english word that means the same, it means something like breaking, but it also means making a specific sound, and it doesn't have to break. for example, if you make the same movement you would use on a twig to break it, but you use it on a straw or a reed, it 'knaks'. both ends are probably still attached to eachother, but it's still kind of broken, it's 'geknakt', 'knacked'(best description would be bend over). and it's also used for determining when weed is done drying and ready for putting in a jar to start curing. when the weed is still too wet the stem will bend, when it's too dry it will break, when when it's exactly right it will 'knak', it will kind of break but not completely, and it will make a specific 'knak'-sound.