diarrhea of the thumb
The same as diarrhea of the mouth except it occurs when a person just can't stop texting useless information. They initially text you with a valid or important text and then it continues text after text and just won't stop. You feel like throwing your phone off a bridge to make it stop.
Normal person - "Joe Thumb just texted me a question. I sure hope his diarrhea of the thumb doesn't flare up or he'll be texting me for hours!"