Spanish grammer

In Spanish 2 Lesson 9.4 Cine They say.
Bueno, I nos matamos de la rise.
Translation.  Well, we couldn't stop laughing.
Since matamos is the we conjugation of matar which means to kill, I do not understand this at all.
 

Well, matar = to kill, and matarse = to be killed or to kill oneself.  It appears they are using a reflexive version of matar, a verb where the subject is the same as the object.  If we are trying to kill our laughter, then we are trying to stop something we are doing.  So, nos matamos = we killed ourselves, and by extension I guess nos matamos de la rise = we killed our laughter.  But that is not what the translation says.

Is this a mistake or is this a colloquial expression that means the opposite of what is written?  Maybe it is a typo and should be "no matamos de la rise".

The intent is more: "We died laughing."

btw, I'm too lazy to look up the lesson, but I think it's ...nos matamos de la risa.

Well, that makes a lot more sense.  I did look up the lesson and they gave "we could not stop laughing" as the translation.  I like "we died laughing" better where "nos matamos" translates to "we died" in the metaphorical sense.

I used the expression in Spain once after seeing a movie and the people I talked to understood the phrase perfectly.