GCU Just Read the Instructions and GCU Of Course I Still Love You are both from The Player of Games. IIRC they were involved in blackmailing Morat Gurgeh into his mission to the Empire of Azad.
http://www.tor.com/blogs/2015/01/elon-musk-iain-m-banks-just-read-the-instructions
A Pun Involving Travel 