Built like the gable end o' a fiver
Someone who is slim built like the thin end of a five pound note.
Person 1: "are you going for a run"
Person 2: "no a dinnae dae that, you dinnae need tae either, yer built like the gable end o' a fiver
Person 2: "no a dinnae dae that, you dinnae need tae either, yer built like the gable end o' a fiver