hi bye Share definition Flag A way to say hello and good bye at the same time, used when you see someone for the first time that day but have to leave immediately. You wake up and are running late and see your girlfriend and say "Hi bye" then run out the door. hi bye by Westley E April 12, 2008 0 0 Get merch Get the hi bye mug. Buy Now — $32.95 See more merch