Is It A Trunk or A Brief? In the case of Cellblock 13’s Hydro Square Brief, the answer is “yes” and “hell to the JEAH!” Insanely comfortable and way easy on the eyes, this body-hugging design is breathable, lighter than air, and sexy-AF. Perfect for everyday wear, hardcore gym sessions, and equally hardcore underwear parties. This design won’t last long, so grab a pair now before they’re gone for good!