A quality orgasm that includes giggling to replace the customary screaming or moaning, which is pleasant and does not annoy the neighbors.
My GF is a ninja with sex; she's about to cum, so I brace for hurricane-force screams, but she pulls a gigglegasm instead. So cute when her boobs bounce along with it.
A one syllable laugh like "heh" or "hah" that in most cases is used when following a simple statement or comment that is somewhat humorous. Can also be used as a courtesy laugh.
Dude One: "Jebus man, my shoe is tied all funny."
Dude Two: "hah"
Dude One: "Thanks for the gigglet."
Dude Two: "Of course... heh."
To be struck with an incessant laughing/giggle fit that keeps going on and on at inconvenient times, rendering you fucked because now you look weird.
Person 1: *sitting in a classroom which is currently silent then happens to think of a funny line from Pineapple Express that strikes a chord* AhahahahahahahahaHAHAHAbuah! *clutching stomach, tears streaming down face, trying to be quiet but failing*
Gigglegrass is a substance which, when smoked, will induce a general sense of happiness, frivolity and merriment. Giggling is a side-effect of this mood. While normally reserved for the upper echelons of grass quality,
Girl A: What are those silly boys up to?
Girl B: Oh, well you know, someone's been into the gigglegrass a bit!
Girl A: Oh, susan!