A person who idly watches the labours of others while declining to offer assistance or becoming involved. Traditionally a term used by canal bargees when referring to onlookers found clustering around locks and moorings where barges have to stop and the crew engage in sometimes hard physical activity to make progress.
"Don't stuff up at Five Rise Locks or you'll get a cheer from the gongoozlers"
Same as "Whizpop" referring to the BFG series and Roald Dahl books in which the word is used to refer to breaking wind . Whizzpop is a spelling used in the BFG books and newspaper cartoon strips.
BFG drank a bottle of Frobscottle and soon after there was a mighty whizzpop!