Marriage and Tattoo
In October of 2012, Greg and Taylor got matching "27" ankle tattoos. (Source) When asked about this tattoo, Greg will only say it's a significant date. (Source) It is most likely for February 27, 2012, the day Greg and Taylor were married.
A month after Greg and Taylor got their tattoos, Greg turned 27.
Sometime after, Greg began selling "27" shirts on his Onision merchandise store. These shirts mimic sports jerseys.