if you stop to urinate or defecate while traveling, you'll fall behind your companions
Archaic proverb using old distance units (町 chō ≈ 109 m, 里 ri ≈ 3.9 km) to humorously warn that even a short toilet break can cause you to lag far behind. Not used in modern conversation.
The proverb 'shōben itchō kuso ichiri' is an old saying that if you relieve yourself while traveling, you'll fall behind your companions.
A fixed proverb from the Edo period or earlier, combining 小便 (urination), 一町 (one chō, about 109 meters), 糞 (feces), and 一里 (one ri, about 3.9 kilometers). The exact origin is uncertain, but it reflects the practical concern of falling behind on foot journeys.