When one person lies so bad that you can see straight through it. In other words, a lie that you know for certain that isn't true. A non-formal term.
"Maxwell went out for dinner last night alone, y'know."
"Yeah, right. That's a dead lie. I saw him with Janet."
"Yeah, right. That's a dead lie. I saw him with Janet."
by Inkbird-Ravenwell November 2, 2017
The ancient pact that unifies truth from brother to brother allowing the validity of a statement to be unquestioned.
PERSON 1 :"Dude, I just sharded all over myself!"
PERSON 2 : "No Lie Dead Serious?"
PERSON 1 : "Dude, No Lie Dead Serious!"
PERSON 2 : "No Lie Dead Serious?"
PERSON 1 : "Dude, No Lie Dead Serious!"
by Honz and Hanz March 9, 2009