Because one of his friends died.
Just like issa got daps or dups on his sticker (:
That's why NAF is one of my favorite players
The "-FLY" suffix that NAF often uses behind his alias is a reference to Joshua "BRUNDLE-FLY" Switzer, a Source-era teammate of his that perished in hit-and-run accident on May 20, 2012.
cause hes fly and looks like sloth