Draw four

They way to end a relationship. It is Similar with the the blue shell.

BF: Last card!
GF: *Pulls out draw four*
BF: Yeah it's over. I'm leaving you.

reverse draw four

When someone threatens to do something shitty to you and you do something similar or worse to them in response.
(yes, it's not allowed in the rules of the card game but retaliation is never really by the book now is it)

Me: He said he was going to send my boob selfies to my boss so I hit him with a reverse draw four and sent the video of him trying to suck his own dick to his mom.