1. An individual that is considered to be a newbie (newb), noobie (noob), or nub.
2. An individual that is new to something.
3. An individual that is not very good at something.
The new guy is a nubski, he has no idea what he's doing.
The foreskin of a nub (or noob, a person who is new and/or plays a game childlike.) Calling someone a nubskin suggests that they play so poorly, there are indeed the foreskin of the nub.
An amalgamation of "Numbskull" and "Skullduggery". Can be employed to describe an amusing, risqué, or banter-incucing act, as perpetrated by a numbskull.
Although not in common usage, would work best used by an Englishman, ideally a gentleman from the East End of London.
"Wot on the Sweet Lord's green erf joo fink you woz ap to larst night 'Arry?"
"Wojoomean boss? We wos jus 'avin a larf. Not mar fault the boys in blue turned ap!"
"Well yore faakin' numskullduggery nearly got us locked ap you tit!"