Reeenius is the fusion of the words '
retarded' and 'genius'. To make it more
retarded, it's written with a triple 'e'. The characteristics of a reeenius person are being
fun, dumb and weird but either way still somehow being intelligent. A reeenius person knows a lot of memes, dumb jokes and insiders (preferably, has dark humor and is sarcastic or ironic).
If you encounter a reeenius person, be aware of getting a lot of dumb jokes thrown at you and (of course) weirdness. If you have someone reeenius as a friend, appreciate it. (You can expect a lot of fun time in the future with them.)
There's also a special term for the group of reeenius
people, 'TeamReeenius'. It also has it's own hashtag, '#TeamReeenius'.