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1.
When someone enters a conversation by blurting something which they think is funny or appropriate to the conversation, but which completely kills the previously enjoyable conversation.
Example 1: Person 1: You slagging me!?

Person 2: Yeah! And!?

Person 1: Do you wanna fight!?

Person 3: Ooh, shit's going down!

(Person 1 and Person 2 leave because of Person 3's un-deahlifying comment).

Example 2: Person 1: Story, lads!?

Person 2: Awh, deahly like, wha!?

Person 3: Hello, guys.

(Person 3 has just un-deahlified the conversation).
by P1mp-My-Giraffe February 11, 2011