LFDY is an abbreviation for "live fast, die young"
This means to live life as you would if it were your last day, with no regrets.
People who LFDY live for fun and fun only, usually with no regards to the consequences.
LFDY is gaining popularity quickly, like the similar abbreviation YOLO.
I don't care what she says, I'll live my life how I want to - #LFDY