my mom is dead 

It can be something said after a "your mom" joke, but that doesn't mean it isn't true.
And it hurts more when your friend thinks that your just trying to make a comeback, and keeps going...

Jeff: Does your mom want her underwear washed with bleach or without?

Carl: My mom is dead.

Jeff: Should I wash the body, too?

Carl: *beats the shit out of Jeff*

my mom is dead by Lolwhat? March 27, 2011

my mom is dead 

Something used after a yo mama joke, not only to make them feel like crap, but also to ruin everyones fun.

Joe-Yo mama is so poor, she goes to Kentucky fry chicken's to lick other people's fingers.

Chris-My mom is dead...

Joe-*looks sadly at Chris*

my mom is dead by Roger D January 23, 2005

My Mom Is Dead 

It is the most common comeback against a Yo Mama joke. Used in an emergency when one can't think of anything to say. Using it automatically results in Fail for being such a lulzkiller. Please note that this is NOT the ultimate comeback

Bob: Btw, can you get my wallet for me? I left it on your mom's dresser.
Drew: My mom is dead
Bob: That explains why she wasn't screaming so much

My Mom Is Dead by Sundance Kid September 17, 2007