Or, in other words, is
called something? Does this specific phenomenon have a name? Could you refer to it generically, as in, "The screen was filled with [the term]"
You get it by "mashing your keyboard" and I once saw keyboard mash associated with it, but I'm not sure if it was just describing the action or naming the product.
Likely if you referred to it by producing it in brief, i.e., "asdfasdf", people would know what you're talking about—but I started wondering about a general term after noting that my own version of this, tumbling out of a Dvorak layout, looks different:
It seems there might be a space for a generic descriptor, given QWERTZ or AZERTY-specific variations, or possible equivalents on more esoteric devices (like stenotypes).