From Wiktionary, the free dictionary
streak of piss (plural streaks of piss)
- (slang, derogatory, vulgar) A tall, thin person.
1997, Robert Coover, John's Wife[1], Simon & Schuster, →ISBN, page 348, →ISBN:But wait: wasn't that the thin streak of piss who stole the truck?
2005, Steve Rudge, A Guardsman's Lot[2], AuthorHouse, →ISBN, page 329, →ISBN:Some tall, skinny streak of piss of a Grenadier Officer, who commanded the boys Company, asked if I would play rugby for the Company.
2018, Nathan Burrows, Blind Justice: A Legal Thriller[3], →ISBN, →ISBN:“I mean, come on, you and me? We're both big guys. He's not. He's a streak of piss, smaller than David, and got to be in his fifties at least.”
- Rick Jolly (2018) Jackspeak: A Guide to British Naval Slang & Usage[4], Bloomsbury, →ISBN, →ISBN: “streak of piss - a tall, gangling and thin person”