lmtd 

This is another one of those internet/text message abbreviations.
In brief: lmtd = laugh(ed/ing) myself to death
As an extreme degree of hysterical laughter, this a step up from rofl or lmao.

"Dude, did you see the Billy Mays auto-tuned vid?"

"Yeah, lmtd!!"

lmtd by JD "Lennon" November 30, 2009

LMTDAKTSK

An acronym that stands for: Laughing Myself To Death After Killing Twenty six kids.

Did you hear about that shooting? I bet that guy is so LMTDAKTSK right now.

LMTDAKTSK by Miguel Sanchezzzz December 14, 2012