What are surreptitious?

Some articles on surreptitious:

General Protection Fault (webcomic) - Crossovers
2004, not knowing it was The Gamester, the superdimensional being that oversaw Surreptitious Machinations, that sent them back ... Newshounds covered the Battle of New York during Surreptitious Machinations ... Desk, User Friendly, and Sluggy Freelance were all featured during Surreptitious Machinations as well when Ki was trying to find work after GPF Software's collapse ...
General Protection Fault (webcomic) - Characters - Minor Characters
... Since Surreptitious Machinations, he has been separated from the time stream, and works for The Gamester ... plans, after apparently designing her mind control chip prior to Surreptitious Machinations before she abandoned them and told him to straighten up his life ... Nadda (Surreptitious Machinations), or Dr ...
Project MKDELTA
... Both MKULTRA and MKDELTA involved the surreptitious use of LSD and other biochemicals in clandestine operations MKULTRA was a domestic program whose ... The final phase of LSD testing involved surreptitious administration to unwitting non-volunteer subjects in normal life settings by undercover officers ...

More definitions of "surreptitious":