That's what's in... I take it you do not listen to rap, because you'd know Drake brought out all that YOLO stuff so now it's all extra popular. "You only live once that's the motto n---- YOLO, and we bout it everyday everyday everyday."
The "swag" and "Yolo" are the current hot selling merchandise. The "Yolo" slang stands for "You only live once" and are meant to encourage people to live at their best given that the is no second chance in life.