A Sambrook is a person that asks too many questions about a particular event. You ask them on a nightout and they immidatley want to know who's coming, what time, where, what should they wear, what's the occasion. By doing this they take all the fun out of the event before its even started!
Harry wanna come to a BBQ at mine on Sat? "what time does it finish,who's going, what we having, do i need to do anything? For Christ sake Harry don't do a fucking Sambrook, you coming or not?