The act of a person falling out of their character and/or breaking the rules that apply to their characters and/or the environment their character roleplays in.
Billy decides to pull his Shank and decides to stab everyone for no reason at all.
Billy: rekt noobs
Victims: Fail Roleplay! Why you randomly killing us?
Billy participates in a roleplaying environment where there are no special super powers allowed. Johnny pulls a gun, and instead of Billy showing gun-fear to the gun of Johnny, he fail roleplays.
Billy: *grabs the gun all of the sudden and kills Johnny out of the sudden
Johnny: Fail Roleplay! You're supposed to show gun fear!
Billy just got killed in that same environment and instead of forgetting all his memories... Billy decides to fail roleplay. Yeah, again.
Billy: *runs back to where he did with his weapon and shoots everyone*
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