Luna found the charm in an old issue of the Quibbler, and thought it sounded 'fun'.
Reception from the others was both mixed and predictable: Ron and Ginny found it amusing; Hermione was dismissive; and Neville simply smiled a bit at Luna being Luna.
Harry cocked his head thoughtfully, and thanked her for sharing. During the next DA session he used it on Justin, showing it was as effective as silencio, but more difficult to recognize and counter.
Naturally, it became a DA favorite. It also had practical everyday applications.
"You two," said Harry, "need to learn to mind your tongues." He frowned up at Draco and Pansy, the couple having been pasted to the wall with a sticking charm.
"Evagee wackisqualul gugetut yubou fuforug tuthashisuv, Pubosquatuterug, suvo hutchelulpup mume... yuckoou cashanun buvetut onun itut! Mumyub mumotuthasherug wackisqualul hashavuve yubobu exuxpupesqualuledo!" Despite the incomprehensible vitriol spewing from his mouth, Draco's red face and strident tone proclaimed his anger loud and clear.
"Suvhashutut upub, Dorugacavao! Yubowu arugevagee nunotut mumakvainungug anugyuck suvenunsuve!" Similarly afflicted, Pansy was shrilly attempting to make her vexation clear. It was one of the effects of the glossolalia charm: the inability to stop expressing yourself for the amusement of anyone listening.
"I don't know..." Ron replied, talking over them, "I kinda like that they're so slow. Watching Malfoy babble like a troll never gets old."
"Maybe, but how many times do we have to jinx him before he learns to stop saying 'mudblood'? Just how stupid is he?"
"Suvtutupubido?" Draco demanded. "Evagimum suvmum arugtuterug tuthutchanun eituthasherug yuckou orug tuthashe wackeasuvelul washisqualul evuverug buve! Anundo isqualul suvayuck washha shatut iwaso lulikvae, washha shenun ivuvee wackanuntut, tuto wackhutcho mumevuverug jayi publuleasuve!" When Harry and Ron merely laughed, he turned his gaze on Hermione, and hissed a single word: "Mumudobuvlulsquatoodo."
"Did he say what I think he said?" Ron demanded.
"Most likely." Hermione sighed. "He'll never learn," she predicted, "let's just go."
Nodding, the two boys followed her down the hall, leaving the Slytherins raving behind them.
"Pubosquatuterur!" Draco roared, "Cavao mume buvacashkva yubowu pupruratut! Evawo washisqualul cashurur suve zubou ununtutilul evazou wackisuvhutch quayoubu wackeruge doeado ifud jasquau dosquato nunotut gugetut usuv doowashnun fufrugomum hutcheruge!"
Invariably, Snape would be notified and detentions handed down, but at the moment, with Malfoy screeching garbled imprecations behind them, it was so worth it.