This spell functions as symbol of death, except that all creatures within 60 feet are affected with uncontrollable laughter (as hideous laughter) for 1 round per caster level.
A creature whose type is different from the caster’s receives a +4 bonus on its saving throw, because humor doesn’t “translate” well.
My question is: does the Creature Type caveat in Hideous Laughter carry over to Symbol of Laughter? Would an Outsider gain a +4 bonus on its save vs. a Symbol of Laughter cast by a Humanoid?
My thinking is no, since Symbol of Laughter's FUNCTION is similar to Symbol of Death, and only its EFFECT is similar to Hideous Laughter. Still, I'd like to hear from others on this.
since it says "as hideous laughter" then the +4 bonus to save would carry over since it's part of the spell description of hideous laughter.