There is a strain called Big Laughing which is meant to do this.

I never tried it myself.
stinkyattic Reviewed by stinkyattic on . Diff. Strains Anyone know of a good strain that gives you those crazy laughing fits. Like I never know what strain it is that I get but sometimes the highs are just all laughing my ass off, and then there are the ones that are really introspective. So which one makes shit more funny, sativa or indica? Rating: 5