Long before punk, drainpipes were originaly popular in the mid to late fifties amongst Teddy Boys, often coupled with a velvet-collared drape jacket to form a suit.
Super narrow, they sometimes have a small split at the bottom of the outside seam.
Person 1: Check that guy's quiff! And what a snappy dreser!
Person 2: Yes, they say he has the narrowest drainpipes in Glasgow.