Goo

Look it up at Wiktionary.

Laloth claimed to have kept "a few vials of [Slalvok's] intestinal goo" as a "souvenir". (AUDIO: Maker's Wish: After Dark - Slalvok ^[+]Loading...["Maker's Wish: After Dark - Slalvok (audio story)"])

Behind the scenes

In non-valid sources

According to Cam, a Blobalottaspannaboldagrizzyquizzymashupalous was only considered dangerous shortly after eating, at which point they could "explode goo". (TV: The Doctor, Doctor Returns! ^[+]Loading...["The Doctor, Doctor Returns! (TV story)"])