We communicated with pithy, rather monosyllabic thoughts: viz. Run, Jump, Where? Left, Up, Duck, ect. (This latter was an observation I made on the edge of a lake. Nathaniel unfortunately took it as a command, which resulted in our temporary immersion.) We didn't ever quite say Ug, but it was a close-run thing.

Bartimaeus Trilogy, Book Three: Ptolemy's Gate (ed. Disney-Hyperion, 2005) - ISBN: 9780786818617