Created in 2011 by Jevastus Destinus, this slang means a very hard laugh you had that you got 6-pack abs as a result of laughing.
Alternatives: 6-pack abs laugh, 6-p laugh, six-pack abs laugh, six-pack laugh, s-p laugh
Jevastus: Yo, you know what a 6-pack laugh is?
Some dude: Hahahahahhahahahaha.
A laugh that is so intense that you feel your ab muscles are getting stronger from it. Occurs when you are laughing very hard about something and your abs start to get sore from it.
George: Whoa man, you look ripped! Do you work out a lot?
Nathan: Nah, these muscles come from all the 6-pack laughs!