rilly Share definition Flag A misspelling of really. Often done on accident by idiots, it may be used on purpose in mockery or sarcasm. Guy1: Hey, my name is Guy1 or other similarly obvious statement Guy2: OH RILLY?? rilly by flatulent fred October 11, 2004 0 0 Get merch Get the rilly mug. Buy Now — $32.95 See more merch