CafePress.com Day

CafePress.com Day is the 2nd holiday in Bluth, the day presumably celebrates CafePress (or CafePress.com (the company's domain name)).

"Sequel"
For the 8th day of Bluth, CafePress.com Day II is celebrated, it is unknown why a "sequel" of the CafePress.com Day was created, but it could possibly be due to popularity.