Oh, I know, that was just my attempt at making it humorously agrammatical, with very little reason to suspect that it was even "correctly incorrect" ;P At least in German, I've heard "kein" and "nicht" used redundantly in a Munich accent, and I was under the impression that the redundant usage of double-or-more negatives was simply a common feature of highly colloquial speech in many languages (especially Germanic languages). Granted, I had no reason to suspect that that might apply to Dutch, soooo...sorry! :P
I disagree because in English if you have two negatives it creates a positive, so you're basically saying you do need a man. When people say "I don't know nothing" it's improper and technically means they know something. I find a lot of French Canadians have a tendency to speak that way only because in French the proper way is a double negative ("Je n'en sais rien" though often incorrectly spoken as "J'en sais rien").
I don't know about German, but in Dutch, it's not a separable verb. It's just a combination of words that has a meaning (so there is no form of the verb where 'nodig' and 'hebben' are merged in one word).
'Nodig' can be an adjective and an adverb and means 'necessary'. The combination 'nodig hebben' means 'to need' (I think it's 'brauchen' in German ;-).
Why is hebben used in this sentence, when it is not translated into English? What role does it play in the Dutch sentence? I am confused.
Ik moet Nederlands spreken
You'll learn about modal verbs later in the tree. I guess if you really wanted to use an infinitive phrase, you could say "Ik heb nodig om Nederlands te spreken" but I think the first option is the better one (assuming by "need" you meant "have to").