Wank is the slang British English term for Masturbation.
A wankation is any day(s) off taken for the sole purpose of releasing steam and masturbating several times a day.
Applies to both males and females.
John: Yeah, my boss has been busting my balls for the quarterly report deadline coming up. Luckily, I've got a long 5 day wankation coming up next week. My target is going to be 8 times a day every day, wish me luck.
Jane: Oh John that is impressive, no one has ever sustained that many wanks in 5 days. You are one lucky guy.
*John thinking to himself: Ummm, maybe I ask her Jane to join me, we can mutual wankation the hell out of each other*