Though i have no idea what the noun is, my mind has adjusted itself to automatically assuming there is some sexual meaning, when i see a question begin with the words "how long is" and other people put smileys next to it.
Anyway, at my own risk, ill bite, and give my final answer as "however long you want it to be".
Either way, i fail to see the point of this exercise as, from my experience, I pass the basic test for determining whether someone is Dutch or not - I speak perfect English.
Yes ACF. Its possible to make jokes about the Dutch without mentioning prostitutes.