This is a Montreal (which has a great public-transport system) term, that I first heard in the late 1950's. A tweezot is a pervert who gets down on his knees to
suck the farts out of the cushions of the back bench seat of a bus,
particularly if an
attractive person has just relinquished that seat. The back seat was favoured because on the older Montral busses the row of seats in front of it had a sort of panel that blocked the driver's view of anyone crouching down there. (The busses have since been redesigned.)