"And what are Slytherin and Hufflepuff?"
"School houses. There's four. Everyone says Hufflepuff are a lot o' duffers, but --"
"I bet I'm in Hufflepuff" said Harry gloomily.
(Harry Potter and the Sorcerer's Stone)
I bet there should be are in there’s four, but I’m not quite sure if there be is or are in Hufflepuff are a lot o’ duffers. (I guess it may depends on which is the head of a lot o’ duffers: lot or duffers)