This is to share the decoded meaning of Sehun's IG username: XLKSLB_CCDTKS (if you are yet to discover)

X iumin

L uhan

K ris

S uho

L ay

B aekhyun

C hen

C hanyeol

D o

T ao

K ai

S ehun

They're EXO's initials arranged from oldest to youngest in age.
So Sehun wasn't really typing nonsense :) God bless his soul for being so smart.

And Tao for being a loving panda with his IG update last midnight PST:

(c)