In Q Speak this is a nice way of saying that a garment is tighter on the body than you'd expect. "Neat" around the waist means that it's not going to fit you unless you get a larger size.
Or your bum's too big.We used to say it’s too bliddy small!
Or, 'You won't like what you look like from behind'My mother often used the phrase, "well, it fits where it touches"