One of Gdragon's tattoos is a dragon ball with eight stars from the anime Dragon Ball Z. The eight repesents his lucky number because he was born on August 18, 1988, so eight is a lucky number to him, even though there are only seven dragon balls in the anime.
"I have this disease-like need to try to create something new. When you're kind of being chased, and everything you do goes so well, you develop this sickness and a sense of need to constantly do something different." - G-Dragon