What is Rilly?
1.
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??
2.
instead of saying really people put rilly
as in rilly gay
lolz0rz taht waz rilly funi haha
w0w taht joek waz amayzingz