What is Roll Like a Buffalo/RLAB?
Roll Like a buffalo came from the original version of Two moons. In the teaser and the EXO showcases, Kris raps “Roll Like a Buffalo”.

What is “Enjoy the Mayo”?
Enjoy the Mayo is a misheard lyric from EXO-M’s version of “History”. The original lyrics were “Listen, 感覺到沒有” —> “Listen, gan jue dao mei you?” which means “Listen, do you feel it?”

What is the deal with Chen and gulls?
In the beginning of EXO-M’s “What is Love” Chen says “Girl, I can’t explain what I feel.” And since he has an accent when speaking English, the word girl sounds like gull.

Why is Luhan called a deer?
His name in Chinese is 鹿晗. 
鹿 also means deer. And that’s his surname. So his surname actually means deer.
I believe this nickname came from the Chinese fans who sometimes call him 鹿鹿 or 小鹿, meaning little deer. 

Why are there jokes about Lay and unicorns?
Lay’s special power is bringing things back to life. And his symbol is a unicorn. 

What is the “Derp Squad”? 
The derp squad consists of Chanyeol, D.O., and Sehun. They are called that because they derp a lot. 

Why is Chen a troll?
So on the official fan message board for EXO, a fan asked Chen to reply to him (I think it was a male fan) and he kept asking but Chen didn’t respond. So the fan said “Just a dot (.) will do! Please” And Chen literally sent him a . That’s why we say he’s a troll >.<
He also replied “I love you” when a fan wanted to hear him tell a joke.