I think cyber Monday is a mainly US thing. Nevertheless it sounds like a great excuse to promote bitcoin. Black Friday/Bitcoin Friday is already a fairly big thing in bitcoinland, but we can always use more events.
For many years people in the USA tended to start their xmas shopping the day after thanksgiving (since its a holiday day but the holiday already passed there's nothing to do -- its also a great bar night!). That became called "black friday" because believe it or not its the first day of the year most retail stores end up switching from a loss to a profit (and a loss is traditionally designated with red ink, a profit black in handwritten act books).
Back before the internet was ubiquitous it was at the workplace first -- especially the high speed internet that made looking a product photos a lot easier then using the "world wide wait" of dial-up. So there was a good 5 year period from about 96 to 01 (your results will vary depending on how techie your location was) where people would do their online holiday shopping at work. So online holiday shopping was easiest the monday after thanskgiving when everyone went back to work. AFAIK, it is questionable whether many online vendors really saw a significant uptick on purchases on that day (after all, its not "really" allowed to shop during work except during lunch break or after hours -- but at the same time back then there was no infrastructure for companies to track employees web accesses anyway), but its definitely clear that the online vendors needed a marketing gimmick to raise awareness of online shopping and compete with Black Friday so they created the term Cyber Monday.
Back then, linking your bank account to paypal (so they could just automatically take money from you as you spend) was just as weird and scary as bitcoin is today! Hopefully in another 5-10 years, this "pull" model of payment will return to its rightful "weird" and "scary" status!