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10.
"Laughing my butt off"

"Laughing my boobs off"

"Laughing my balls off"

They're all implying the same thing; you're laughing incredibly hard. It's often a replacement for "lmao" (laughing my ass off) for people who prefer not to curse in their interweb acronyms.
Person A: *tells a funny story*
Person B: LMBO
Person A: wait, but you're a girl, you don't have balls!
Person B: it can also mean "laughing your boobs off"
Person A: what if you have neither? (somehow)
Person B: then it can mean, "laughing your butt off"
by A Flying Turtle June 24, 2010
 
1.
Laughing my butt off. A less dramatic version of LMAO.
I fell off the cliff and died.
LMBO!
by Kevin January 18, 2005
 
2.
alternate way of expressing extreme laughter, to the extent where ones burca falls from ones head. Not enough for one to 'laugh ones ass off', but enough for a burca to fall.
Sarah - "Tacco Tacco BURRITO!!"
Roxy - "That's so funny LMBO!!"
by ghandishoes June 26, 2010
 
3.
lmbo: samething as lmao unless the b is used differently. Ex. lmbo: laugh my boobs off, laugh my balls off or just laugh my butt off
person1:omg i fell down the stairs person2:lmbo
by Independent1011 January 14, 2010
 
4.
Acronym for "Laughing my black off". Popularized by Mike Turpinseed Jr. in early 2013.
Something so funny, that you lose skin pigment.
"Mike Turpinseed Jr. is one funny mothafucka!"

"Lmbo!"
by denys petrov January 10, 2013
 
5.
Let my boner out
When working around the bases with the woman of your dreams you slowly whisper lmbo in her ear.
by DandyDon6969 February 12, 2010
 
6.
Laughed My Butt Off.
It made me LMBO.
by dsscheibe February 17, 2011
 
7.
before it meant "laughing my butt off"
but now the meaning has changed to "laughing my BOOBS off"
guy: that was so funny
girl: yeah i was lmbo (laughing my boobs off)!
by Plaidtastic January 01, 2009