num skull 

num·skull also numb·skull
NOUN.
A stupid person
num (variant of numb) + skull.

How Could You get Hit BY A parked car,you Num Skull!

num skull by CHRIS MCGAHA May 30, 2006

Numskullduggery 

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!"

Numskullduggery by Kilpin May 29, 2007