Babbling
From Wakipedia
What is Babbling?
This philosophical wonder, (thingy no one can truly explain), is actually caused by proximity to running water.
"Running water?", (some of you might inquire).
Well, yes. It turns out that small microorganisms inhabit many streams and rivers. (See: Babbling Brook) These small parasitic life forms end up being consumed, drank, included in a hot new drink recipe that no one sane should ever actually try. (It probably involves tequila)
Once in the bloodstream, these organisms industriously make their way to the brain. Note industriously here, not casually strolling, or otherwise taking it easy, enjoying the sights, or even noticing that nice new growth near your large intestine, (which is rapidly becoming the 'IN' place for nightlife in your digestive tract).
Where were we? Oh yes...
They industriously travel to the brain, filled with self importance and motivated to give their host the benefits of their great wisdom. (Said wisdom's actual value being debatable, but they think quite highly of it)
Once in the brain area, they seek out the part on the mind responsible for speech, and vocalizing. They then proceed to change the mental structures and memories of speech, all somehow limiting these changes to short term memory. (It is put forth they would do this to people's long term memory, resulting in a permanent change, but this memory has a redundant backup system which undoes all such changes within a few hours, effectively blocking it)
In any case, the upshot of the whole thing, is that the affected person begins to speak in this revised version of their language. This new language variation, which is consistent only with that spoken by other victims of this parasite, causes the speaker to uncontrollably utter the first thought to have the misfortune of stumbling into their minds.
If another victim is near, this invariably triggers a similar reaction in them, and the two or more will begin speaking in this new language to each other, each helplessly trapped in the parasite's grip
To anyone not affected by this parasite, all that will be heard is "Blah blah blah", as they have not had their vocal centers redone recently by parasites. This is probably for the best, since they would be unlikely to make much sense of it any way.
