Noisily, senselessly agitated and talking. Almost always followed by "idiot." Blithering is likely a portmanteau of blather and dither. Three words for the price of one! You don't get that value from a regular dictionary.
In case you were wondering, it's a corgi trying to get out of a tent.
AnimalsCorgisLonger legs neededTentsAnimals that wouldn't survive in the wild
German designer Wolfram Kampffmeyer, as Paperwolf, creates geometric paper animals for you to make yourself. They come flat-packed with folding instructions. There's a lot of photos at the link, plus many more varieties available at his Etsy shop.
AnimalsDIYGermanyThings to buyMailWhat does it say?