An instance when someone happens to be rolling on the floor laughing with a kid named Maneo. This is an extremely rare occurrence for Maneo is not a very common name. Nonetheless, when a "roflmaneo" is completed, it can be the greatest thing ever.
the beast within you that makes you laugh at completely inappropriate times, like a funeral, a breakup, when someone tells you of an ailment, or a dramatic movie that matters to the person you're watching it with
i was at my girlfriend's grandpa's funeral, and my roflmonster came out at the worst time possible!! i couldn't control it at all, but i didn't care for some reason